diff options
Diffstat (limited to 'Documentation')
35 files changed, 1829 insertions, 700 deletions
diff --git a/Documentation/ABI/testing/sysfs-ata b/Documentation/ABI/testing/sysfs-ata new file mode 100644 index 000000000000..0a932155cbba --- /dev/null +++ b/Documentation/ABI/testing/sysfs-ata @@ -0,0 +1,99 @@ +What: /sys/class/ata_... +Date: August 2008 +Contact: Gwendal Grignou<gwendal@google.com> +Description: + +Provide a place in sysfs for storing the ATA topology of the system. This allows +retrieving various information about ATA objects. + +Files under /sys/class/ata_port +------------------------------- + + For each port, a directory ataX is created where X is the ata_port_id of + the port. The device parent is the ata host device. + +idle_irq (read) + + Number of IRQ received by the port while idle [some ata HBA only]. + +nr_pmp_links (read) + + If a SATA Port Multiplier (PM) is connected, number of link behind it. + +Files under /sys/class/ata_link +------------------------------- + + Behind each port, there is a ata_link. If there is a SATA PM in the + topology, 15 ata_link objects are created. + + If a link is behind a port, the directory name is linkX, where X is + ata_port_id of the port. + If a link is behind a PM, its name is linkX.Y where X is ata_port_id + of the parent port and Y the PM port. + +hw_sata_spd_limit + + Maximum speed supported by the connected SATA device. + +sata_spd_limit + + Maximum speed imposed by libata. + +sata_spd + + Current speed of the link [1.5, 3Gps,...]. + +Files under /sys/class/ata_device +--------------------------------- + + Behind each link, up to two ata device are created. + The name of the directory is devX[.Y].Z where: + - X is ata_port_id of the port where the device is connected, + - Y the port of the PM if any, and + - Z the device id: for PATA, there is usually 2 devices [0,1], + only 1 for SATA. + +class + Device class. Can be "ata" for disk, "atapi" for packet device, + "pmp" for PM, or "none" if no device was found behind the link. + +dma_mode + + Transfer modes supported by the device when in DMA mode. + Mostly used by PATA device. + +pio_mode + + Transfer modes supported by the device when in PIO mode. + Mostly used by PATA device. + +xfer_mode + + Current transfer mode. + +id + + Cached result of IDENTIFY command, as described in ATA8 7.16 and 7.17. + Only valid if the device is not a PM. + +gscr + + Cached result of the dump of PM GSCR register. + Valid registers are: + 0: SATA_PMP_GSCR_PROD_ID, + 1: SATA_PMP_GSCR_REV, + 2: SATA_PMP_GSCR_PORT_INFO, + 32: SATA_PMP_GSCR_ERROR, + 33: SATA_PMP_GSCR_ERROR_EN, + 64: SATA_PMP_GSCR_FEAT, + 96: SATA_PMP_GSCR_FEAT_EN, + 130: SATA_PMP_GSCR_SII_GPIO + Only valid if the device is a PM. + +spdn_cnt + + Number of time libata decided to lower the speed of link due to errors. + +ering + + Formatted output of the error ring of the device. diff --git a/Documentation/ABI/testing/sysfs-devices-power b/Documentation/ABI/testing/sysfs-devices-power index 6123c523bfd7..7628cd1bc36a 100644 --- a/Documentation/ABI/testing/sysfs-devices-power +++ b/Documentation/ABI/testing/sysfs-devices-power @@ -77,3 +77,91 @@ Description: devices this attribute is set to "enabled" by bus type code or device drivers and in that cases it should be safe to leave the default value. + +What: /sys/devices/.../power/wakeup_count +Date: September 2010 +Contact: Rafael J. Wysocki <rjw@sisk.pl> +Description: + The /sys/devices/.../wakeup_count attribute contains the number + of signaled wakeup events associated with the device. This + attribute is read-only. If the device is not enabled to wake up + the system from sleep states, this attribute is empty. + +What: /sys/devices/.../power/wakeup_active_count +Date: September 2010 +Contact: Rafael J. Wysocki <rjw@sisk.pl> +Description: + The /sys/devices/.../wakeup_active_count attribute contains the + number of times the processing of wakeup events associated with + the device was completed (at the kernel level). This attribute + is read-only. If the device is not enabled to wake up the + system from sleep states, this attribute is empty. + +What: /sys/devices/.../power/wakeup_hit_count +Date: September 2010 +Contact: Rafael J. Wysocki <rjw@sisk.pl> +Description: + The /sys/devices/.../wakeup_hit_count attribute contains the + number of times the processing of a wakeup event associated with + the device might prevent the system from entering a sleep state. + This attribute is read-only. If the device is not enabled to + wake up the system from sleep states, this attribute is empty. + +What: /sys/devices/.../power/wakeup_active +Date: September 2010 +Contact: Rafael J. Wysocki <rjw@sisk.pl> +Description: + The /sys/devices/.../wakeup_active attribute contains either 1, + or 0, depending on whether or not a wakeup event associated with + the device is being processed (1). This attribute is read-only. + If the device is not enabled to wake up the system from sleep + states, this attribute is empty. + +What: /sys/devices/.../power/wakeup_total_time_ms +Date: September 2010 +Contact: Rafael J. Wysocki <rjw@sisk.pl> +Description: + The /sys/devices/.../wakeup_total_time_ms attribute contains + the total time of processing wakeup events associated with the + device, in milliseconds. This attribute is read-only. If the + device is not enabled to wake up the system from sleep states, + this attribute is empty. + +What: /sys/devices/.../power/wakeup_max_time_ms +Date: September 2010 +Contact: Rafael J. Wysocki <rjw@sisk.pl> +Description: + The /sys/devices/.../wakeup_max_time_ms attribute contains + the maximum time of processing a single wakeup event associated + with the device, in milliseconds. This attribute is read-only. + If the device is not enabled to wake up the system from sleep + states, this attribute is empty. + +What: /sys/devices/.../power/wakeup_last_time_ms +Date: September 2010 +Contact: Rafael J. Wysocki <rjw@sisk.pl> +Description: + The /sys/devices/.../wakeup_last_time_ms attribute contains + the value of the monotonic clock corresponding to the time of + signaling the last wakeup event associated with the device, in + milliseconds. This attribute is read-only. If the device is + not enabled to wake up the system from sleep states, this + attribute is empty. + +What: /sys/devices/.../power/autosuspend_delay_ms +Date: September 2010 +Contact: Alan Stern <stern@rowland.harvard.edu> +Description: + The /sys/devices/.../power/autosuspend_delay_ms attribute + contains the autosuspend delay value (in milliseconds). Some + drivers do not want their device to suspend as soon as it + becomes idle at run time; they want the device to remain + inactive for a certain minimum period of time first. That + period is called the autosuspend delay. Negative values will + prevent the device from being suspended at run time (similar + to writing "on" to the power/control attribute). Values >= + 1000 will cause the autosuspend timer expiration to be rounded + up to the nearest second. + + Not all drivers support this attribute. If it isn't supported, + attempts to read or write it will yield I/O errors. diff --git a/Documentation/ABI/testing/sysfs-power b/Documentation/ABI/testing/sysfs-power index 2875f1f74a07..194ca446ac28 100644 --- a/Documentation/ABI/testing/sysfs-power +++ b/Documentation/ABI/testing/sysfs-power @@ -99,9 +99,38 @@ Description: dmesg -s 1000000 | grep 'hash matches' + If you do not get any matches (or they appear to be false + positives), it is possible that the last PM event point + referred to a device created by a loadable kernel module. In + this case cat /sys/power/pm_trace_dev_match (see below) after + your system is started up and the kernel modules are loaded. + CAUTION: Using it will cause your machine's real-time (CMOS) clock to be set to a random invalid time after a resume. +What; /sys/power/pm_trace_dev_match +Date: October 2010 +Contact: James Hogan <james@albanarts.com> +Description: + The /sys/power/pm_trace_dev_match file contains the name of the + device associated with the last PM event point saved in the RTC + across reboots when pm_trace has been used. More precisely it + contains the list of current devices (including those + registered by loadable kernel modules since boot) which match + the device hash in the RTC at boot, with a newline after each + one. + + The advantage of this file over the hash matches printed to the + kernel log (see /sys/power/pm_trace), is that it includes + devices created after boot by loadable kernel modules. + + Due to the small hash size necessary to fit in the RTC, it is + possible that more than one device matches the hash, in which + case further investigation is required to determine which + device is causing the problem. Note that genuine RTC clock + values (such as when pm_trace has not been used), can still + match a device and output it's name here. + What: /sys/power/pm_async Date: January 2009 Contact: Rafael J. Wysocki <rjw@sisk.pl> diff --git a/Documentation/DocBook/drm.tmpl b/Documentation/DocBook/drm.tmpl index 910c923a9b86..2861055afd7a 100644 --- a/Documentation/DocBook/drm.tmpl +++ b/Documentation/DocBook/drm.tmpl @@ -136,6 +136,7 @@ #ifdef CONFIG_COMPAT .compat_ioctl = i915_compat_ioctl, #endif + .llseek = noop_llseek, }, .pci_driver = { .name = DRIVER_NAME, diff --git a/Documentation/DocBook/genericirq.tmpl b/Documentation/DocBook/genericirq.tmpl index 1448b33fd222..fb10fd08c05c 100644 --- a/Documentation/DocBook/genericirq.tmpl +++ b/Documentation/DocBook/genericirq.tmpl @@ -28,7 +28,7 @@ </authorgroup> <copyright> - <year>2005-2006</year> + <year>2005-2010</year> <holder>Thomas Gleixner</holder> </copyright> <copyright> @@ -100,6 +100,10 @@ <listitem><para>Edge type</para></listitem> <listitem><para>Simple type</para></listitem> </itemizedlist> + During the implementation we identified another type: + <itemizedlist> + <listitem><para>Fast EOI type</para></listitem> + </itemizedlist> In the SMP world of the __do_IRQ() super-handler another type was identified: <itemizedlist> @@ -153,6 +157,7 @@ is still available. This leads to a kind of duality for the time being. Over time the new model should be used in more and more architectures, as it enables smaller and cleaner IRQ subsystems. + It's deprecated for three years now and about to be removed. </para> </chapter> <chapter id="bugs"> @@ -217,6 +222,7 @@ <itemizedlist> <listitem><para>handle_level_irq</para></listitem> <listitem><para>handle_edge_irq</para></listitem> + <listitem><para>handle_fasteoi_irq</para></listitem> <listitem><para>handle_simple_irq</para></listitem> <listitem><para>handle_percpu_irq</para></listitem> </itemizedlist> @@ -233,33 +239,33 @@ are used by the default flow implementations. The following helper functions are implemented (simplified excerpt): <programlisting> -default_enable(irq) +default_enable(struct irq_data *data) { - desc->chip->unmask(irq); + desc->chip->irq_unmask(data); } -default_disable(irq) +default_disable(struct irq_data *data) { - if (!delay_disable(irq)) - desc->chip->mask(irq); + if (!delay_disable(data)) + desc->chip->irq_mask(data); } -default_ack(irq) +default_ack(struct irq_data *data) { - chip->ack(irq); + chip->irq_ack(data); } -default_mask_ack(irq) +default_mask_ack(struct irq_data *data) { - if (chip->mask_ack) { - chip->mask_ack(irq); + if (chip->irq_mask_ack) { + chip->irq_mask_ack(data); } else { - chip->mask(irq); - chip->ack(irq); + chip->irq_mask(data); + chip->irq_ack(data); } } -noop(irq) +noop(struct irq_data *data)) { } @@ -278,12 +284,27 @@ noop(irq) <para> The following control flow is implemented (simplified excerpt): <programlisting> -desc->chip->start(); +desc->chip->irq_mask(); handle_IRQ_event(desc->action); -desc->chip->end(); +desc->chip->irq_unmask(); </programlisting> </para> - </sect3> + </sect3> + <sect3 id="Default_FASTEOI_IRQ_flow_handler"> + <title>Default Fast EOI IRQ flow handler</title> + <para> + handle_fasteoi_irq provides a generic implementation + for interrupts, which only need an EOI at the end of + the handler + </para> + <para> + The following control flow is implemented (simplified excerpt): + <programlisting> +handle_IRQ_event(desc->action); +desc->chip->irq_eoi(); + </programlisting> + </para> + </sect3> <sect3 id="Default_Edge_IRQ_flow_handler"> <title>Default Edge IRQ flow handler</title> <para> @@ -294,20 +315,19 @@ desc->chip->end(); The following control flow is implemented (simplified excerpt): <programlisting> if (desc->status & running) { - desc->chip->hold(); + desc->chip->irq_mask(); desc->status |= pending | masked; return; } -desc->chip->start(); +desc->chip->irq_ack(); desc->status |= running; do { if (desc->status & masked) - desc->chip->enable(); + desc->chip->irq_unmask(); desc->status &= ~pending; handle_IRQ_event(desc->action); } while (status & pending); desc->status &= ~running; -desc->chip->end(); </programlisting> </para> </sect3> @@ -342,9 +362,9 @@ handle_IRQ_event(desc->action); <para> The following control flow is implemented (simplified excerpt): <programlisting> -desc->chip->start(); handle_IRQ_event(desc->action); -desc->chip->end(); +if (desc->chip->irq_eoi) + desc->chip->irq_eoi(); </programlisting> </para> </sect3> @@ -375,8 +395,7 @@ desc->chip->end(); mechanism. (It's necessary to enable CONFIG_HARDIRQS_SW_RESEND when you want to use the delayed interrupt disable feature and your hardware is not capable of retriggering an interrupt.) - The delayed interrupt disable can be runtime enabled, per interrupt, - by setting the IRQ_DELAYED_DISABLE flag in the irq_desc status field. + The delayed interrupt disable is not configurable. </para> </sect2> </sect1> @@ -387,13 +406,13 @@ desc->chip->end(); contains all the direct chip relevant functions, which can be utilized by the irq flow implementations. <itemizedlist> - <listitem><para>ack()</para></listitem> - <listitem><para>mask_ack() - Optional, recommended for performance</para></listitem> - <listitem><para>mask()</para></listitem> - <listitem><para>unmask()</para></listitem> - <listitem><para>retrigger() - Optional</para></listitem> - <listitem><para>set_type() - Optional</para></listitem> - <listitem><para>set_wake() - Optional</para></listitem> + <listitem><para>irq_ack()</para></listitem> + <listitem><para>irq_mask_ack() - Optional, recommended for performance</para></listitem> + <listitem><para>irq_mask()</para></listitem> + <listitem><para>irq_unmask()</para></listitem> + <listitem><para>irq_retrigger() - Optional</para></listitem> + <listitem><para>irq_set_type() - Optional</para></listitem> + <listitem><para>irq_set_wake() - Optional</para></listitem> </itemizedlist> These primitives are strictly intended to mean what they say: ack means ACK, masking means masking of an IRQ line, etc. It is up to the flow @@ -458,6 +477,7 @@ desc->chip->end(); <para> This chapter contains the autogenerated documentation of the internal functions. </para> +!Ikernel/irq/irqdesc.c !Ikernel/irq/handle.c !Ikernel/irq/chip.c </chapter> diff --git a/Documentation/DocBook/kernel-api.tmpl b/Documentation/DocBook/kernel-api.tmpl index 6899f471fb15..6b4e07f28b69 100644 --- a/Documentation/DocBook/kernel-api.tmpl +++ b/Documentation/DocBook/kernel-api.tmpl @@ -257,7 +257,8 @@ X!Earch/x86/kernel/mca_32.c !Iblock/blk-sysfs.c !Eblock/blk-settings.c !Eblock/blk-exec.c -!Eblock/blk-barrier.c +!Eblock/blk-flush.c +!Eblock/blk-lib.c !Eblock/blk-tag.c !Iblock/blk-tag.c !Eblock/blk-integrity.c diff --git a/Documentation/DocBook/kernel-locking.tmpl b/Documentation/DocBook/kernel-locking.tmpl index a0d479d1e1dd..f66f4df18690 100644 --- a/Documentation/DocBook/kernel-locking.tmpl +++ b/Documentation/DocBook/kernel-locking.tmpl @@ -1645,7 +1645,9 @@ the amount of locking which needs to be done. all the readers who were traversing the list when we deleted the element are finished. We use <function>call_rcu()</function> to register a callback which will actually destroy the object once - the readers are finished. + all pre-existing readers are finished. Alternatively, + <function>synchronize_rcu()</function> may be used to block until + all pre-existing are finished. </para> <para> But how does Read Copy Update know when the readers are @@ -1714,7 +1716,7 @@ the amount of locking which needs to be done. - object_put(obj); + list_del_rcu(&obj->list); cache_num--; -+ call_rcu(&obj->rcu, cache_delete_rcu, obj); ++ call_rcu(&obj->rcu, cache_delete_rcu); } /* Must be holding cache_lock */ @@ -1725,14 +1727,6 @@ the amount of locking which needs to be done. if (++cache_num > MAX_CACHE_SIZE) { struct object *i, *outcast = NULL; list_for_each_entry(i, &cache, list) { -@@ -85,6 +94,7 @@ - obj->popularity = 0; - atomic_set(&obj->refcnt, 1); /* The cache holds a reference */ - spin_lock_init(&obj->lock); -+ INIT_RCU_HEAD(&obj->rcu); - - spin_lock_irqsave(&cache_lock, flags); - __cache_add(obj); @@ -104,12 +114,11 @@ struct object *cache_find(int id) { diff --git a/Documentation/RCU/checklist.txt b/Documentation/RCU/checklist.txt index 790d1a812376..0c134f8afc6f 100644 --- a/Documentation/RCU/checklist.txt +++ b/Documentation/RCU/checklist.txt @@ -218,13 +218,22 @@ over a rather long period of time, but improvements are always welcome! include: a. Keeping a count of the number of data-structure elements - used by the RCU-protected data structure, including those - waiting for a grace period to elapse. Enforce a limit - on this number, stalling updates as needed to allow - previously deferred frees to complete. - - Alternatively, limit only the number awaiting deferred - free rather than the total number of elements. + used by the RCU-protected data structure, including + those waiting for a grace period to elapse. Enforce a + limit on this number, stalling updates as needed to allow + previously deferred frees to complete. Alternatively, + limit only the number awaiting deferred free rather than + the total number of elements. + + One way to stall the updates is to acquire the update-side + mutex. (Don't try this with a spinlock -- other CPUs + spinning on the lock could prevent the grace period + from ever ending.) Another way to stall the updates + is for the updates to use a wrapper function around + the memory allocator, so that this wrapper function + simulates OOM when there is too much memory awaiting an + RCU grace period. There are of course many other + variations on this theme. b. Limiting update rate. For example, if updates occur only once per hour, then no explicit rate limiting is required, @@ -365,3 +374,26 @@ over a rather long period of time, but improvements are always welcome! and the compiler to freely reorder code into and out of RCU read-side critical sections. It is the responsibility of the RCU update-side primitives to deal with this. + +17. Use CONFIG_PROVE_RCU, CONFIG_DEBUG_OBJECTS_RCU_HEAD, and + the __rcu sparse checks to validate your RCU code. These + can help find problems as follows: + + CONFIG_PROVE_RCU: check that accesses to RCU-protected data + structures are carried out under the proper RCU + read-side critical section, while holding the right + combination of locks, or whatever other conditions + are appropriate. + + CONFIG_DEBUG_OBJECTS_RCU_HEAD: check that you don't pass the + same object to call_rcu() (or friends) before an RCU + grace period has elapsed since the last time that you + passed that same object to call_rcu() (or friends). + + __rcu sparse checks: tag the pointer to the RCU-protected data + structure with __rcu, and sparse will warn you if you + access that pointer without the services of one of the + variants of rcu_dereference(). + + These debugging aids can help you find problems that are + otherwise extremely difficult to spot. diff --git a/Documentation/RCU/stallwarn.txt b/Documentation/RCU/stallwarn.txt index 44c6dcc93d6d..862c08ef1fde 100644 --- a/Documentation/RCU/stallwarn.txt +++ b/Documentation/RCU/stallwarn.txt @@ -80,6 +80,24 @@ o A CPU looping with bottom halves disabled. This condition can o For !CONFIG_PREEMPT kernels, a CPU looping anywhere in the kernel without invoking schedule(). +o A CPU-bound real-time task in a CONFIG_PREEMPT kernel, which might + happen to preempt a low-priority task in the middle of an RCU + read-side critical section. This is especially damaging if + that low-priority task is not permitted to run on any other CPU, + in which case the next RCU grace period can never complete, which + will eventually cause the system to run out of memory and hang. + While the system is in the process of running itself out of + memory, you might see stall-warning messages. + +o A CPU-bound real-time task in a CONFIG_PREEMPT_RT kernel that + is running at a higher priority than the RCU softirq threads. + This will prevent RCU callbacks from ever being invoked, + and in a CONFIG_TREE_PREEMPT_RCU kernel will further prevent + RCU grace periods from ever completing. Either way, the + system will eventually run out of memory and hang. In the + CONFIG_TREE_PREEMPT_RCU case, you might see stall-warning + messages. + o A bug in the RCU implementation. o A hardware failure. This is quite unlikely, but has occurred diff --git a/Documentation/RCU/trace.txt b/Documentation/RCU/trace.txt index efd8cc95c06b..a851118775d8 100644 --- a/Documentation/RCU/trace.txt +++ b/Documentation/RCU/trace.txt @@ -125,6 +125,17 @@ o "b" is the batch limit for this CPU. If more than this number of RCU callbacks is ready to invoke, then the remainder will be deferred. +o "ci" is the number of RCU callbacks that have been invoked for + this CPU. Note that ci+ql is the number of callbacks that have + been registered in absence of CPU-hotplug activity. + +o "co" is the number of RCU callbacks that have been orphaned due to + this CPU going offline. + +o "ca" is the number of RCU callbacks that have been adopted due to + other CPUs going offline. Note that ci+co-ca+ql is the number of + RCU callbacks registered on this CPU. + There is also an rcu/rcudata.csv file with the same information in comma-separated-variable spreadsheet format. @@ -180,7 +191,7 @@ o "s" is the "signaled" state that drives force_quiescent_state()'s o "jfq" is the number of jiffies remaining for this grace period before force_quiescent_state() is invoked to help push things - along. Note that CPUs in dyntick-idle mode thoughout the grace + along. Note that CPUs in dyntick-idle mode throughout the grace period will not report on their own, but rather must be check by some other CPU via force_quiescent_state(). diff --git a/Documentation/arm/00-INDEX b/Documentation/arm/00-INDEX index 7f5fc3ba9c91..ecf7d04bca26 100644 --- a/Documentation/arm/00-INDEX +++ b/Documentation/arm/00-INDEX @@ -6,6 +6,8 @@ Interrupts - ARM Interrupt subsystem documentation IXP2000 - Release Notes for Linux on Intel's IXP2000 Network Processor +msm + - MSM specific documentation Netwinder - Netwinder specific documentation Porting diff --git a/Documentation/arm/msm/gpiomux.txt b/Documentation/arm/msm/gpiomux.txt new file mode 100644 index 000000000000..67a81620adf6 --- /dev/null +++ b/Documentation/arm/msm/gpiomux.txt @@ -0,0 +1,176 @@ +This document provides an overview of the msm_gpiomux interface, which +is used to provide gpio pin multiplexing and configuration on mach-msm +targets. + +History +======= + +The first-generation API for gpio configuration & multiplexing on msm +is the function gpio_tlmm_config(). This function has a few notable +shortcomings, which led to its deprecation and replacement by gpiomux: + +The 'disable' parameter: Setting the second parameter to +gpio_tlmm_config to GPIO_CFG_DISABLE tells the peripheral +processor in charge of the subsystem to perform a look-up into a +low-power table and apply the low-power/sleep setting for the pin. +As the msm family evolved this became problematic. Not all pins +have sleep settings, not all peripheral processors will accept requests +to apply said sleep settings, and not all msm targets have their gpio +subsystems managed by a peripheral processor. In order to get consistent +behavior on all targets, drivers are forced to ignore this parameter, +rendering it useless. + +The 'direction' flag: for all mux-settings other than raw-gpio (0), +the output-enable bit of a gpio is hard-wired to a known +input (usually VDD or ground). For those settings, the direction flag +is meaningless at best, and deceptive at worst. In addition, using the +direction flag to change output-enable (OE) directly can cause trouble in +gpiolib, which has no visibility into gpio direction changes made +in this way. Direction control in gpio mode should be made through gpiolib. + +Key Features of gpiomux +======================= + +- A consistent interface across all generations of msm. Drivers can expect +the same results on every target. +- gpiomux plays nicely with gpiolib. Functions that should belong to gpiolib +are left to gpiolib and not duplicated here. gpiomux is written with the +intent that gpio_chips will call gpiomux reference-counting methods +from their request() and free() hooks, providing full integration. +- Tabular configuration. Instead of having to call gpio_tlmm_config +hundreds of times, gpio configuration is placed in a single table. +- Per-gpio sleep. Each gpio is individually reference counted, allowing only +those lines which are in use to be put in high-power states. +- 0 means 'do nothing': all flags are designed so that the default memset-zero +equates to a sensible default of 'no configuration', preventing users +from having to provide hundreds of 'no-op' configs for unused or +unwanted lines. + +Usage +===== + +To use gpiomux, provide configuration information for relevant gpio lines +in the msm_gpiomux_configs table. Since a 0 equates to "unconfigured", +only those lines to be managed by gpiomux need to be specified. Here +is a completely fictional example: + +struct msm_gpiomux_config msm_gpiomux_configs[GPIOMUX_NGPIOS] = { + [12] = { + .active = GPIOMUX_VALID | GPIOMUX_DRV_8MA | GPIOMUX_FUNC_1, + .suspended = GPIOMUX_VALID | GPIOMUX_PULL_DOWN, + }, + [34] = { + .suspended = GPIOMUX_VALID | GPIOMUX_PULL_DOWN, + }, +}; + +To indicate that a gpio is in use, call msm_gpiomux_get() to increase +its reference count. To decrease the reference count, call msm_gpiomux_put(). + +The effect of this configuration is as follows: + +When the system boots, gpios 12 and 34 will be initialized with their +'suspended' configurations. All other gpios, which were left unconfigured, +will not be touched. + +When msm_gpiomux_get() is called on gpio 12 to raise its reference count +above 0, its active configuration will be applied. Since no other gpio +line has a valid active configuration, msm_gpiomux_get() will have no +effect on any other line. + +When msm_gpiomux_put() is called on gpio 12 or 34 to drop their reference +count to 0, their suspended configurations will be applied. +Since no other gpio line has a valid suspended configuration, no other +gpio line will be effected by msm_gpiomux_put(). Since gpio 34 has no valid +active configuration, this is effectively a no-op for gpio 34 as well, +with one small caveat, see the section "About Output-Enable Settings". + +All of the GPIOMUX_VALID flags may seem like unnecessary overhead, but +they address some important issues. As unused entries (all those +except 12 and 34) are zero-filled, gpiomux needs a way to distinguish +the used fields from the unused. In addition, the all-zero pattern +is a valid configuration! Therefore, gpiomux defines an additional bit +which is used to indicate when a field is used. This has the pleasant +side-effect of allowing calls to msm_gpiomux_write to use '0' to indicate +that a value should not be changed: + + msm_gpiomux_write(0, GPIOMUX_VALID, 0); + +replaces the active configuration of gpio 0 with an all-zero configuration, +but leaves the suspended configuration as it was. + +Static Configurations +===================== + +To install a static configuration, which is applied at boot and does +not change after that, install a configuration with a suspended component +but no active component, as in the previous example: + + [34] = { + .suspended = GPIOMUX_VALID | GPIOMUX_PULL_DOWN, + }, + +The suspended setting is applied during boot, and the lack of any valid +active setting prevents any other setting from being applied at runtime. +If other subsystems attempting to access the line is a concern, one could +*really* anchor the configuration down by calling msm_gpiomux_get on the +line at initialization to move the line into active mode. With the line +held, it will never be re-suspended, and with no valid active configuration, +no new configurations will be applied. + +But then, if having other subsystems grabbing for the line is truly a concern, +it should be reserved with gpio_request instead, which carries an implicit +msm_gpiomux_get. + +gpiomux and gpiolib +=================== + +It is expected that msm gpio_chips will call msm_gpiomux_get() and +msm_gpiomux_put() from their request and free hooks, like this fictional +example: + +static int request(struct gpio_chip *chip, unsigned offset) +{ + return msm_gpiomux_get(chip->base + offset); +} + +static void free(struct gpio_chip *chip, unsigned offset) +{ + msm_gpiomux_put(chip->base + offset); +} + + ...somewhere in a gpio_chip declaration... + .request = request, + .free = free, + +This provides important functionality: +- It guarantees that a gpio line will have its 'active' config applied + when the line is requested, and will not be suspended while the line + remains requested; and +- It guarantees that gpio-direction settings from gpiolib behave sensibly. + See "About Output-Enable Settings." + +This mechanism allows for "auto-request" of gpiomux lines via gpiolib +when it is suitable. Drivers wishing more exact control are, of course, +free to also use msm_gpiomux_set and msm_gpiomux_get. + +About Output-Enable Settings +============================ + +Some msm targets do not have the ability to query the current gpio +configuration setting. This means that changes made to the output-enable +(OE) bit by gpiolib cannot be consistently detected and preserved by gpiomux. +Therefore, when gpiomux applies a configuration setting, any direction +settings which may have been applied by gpiolib are lost and the default +input settings are re-applied. + +For this reason, drivers should not assume that gpio direction settings +continue to hold if they free and then re-request a gpio. This seems like +common sense - after all, anybody could have obtained the line in the +meantime - but it needs saying. + +This also means that calls to msm_gpiomux_write will reset the OE bit, +which means that if the gpio line is held by a client of gpiolib and +msm_gpiomux_write is called, the direction setting has been lost and +gpiolib's internal state has been broken. +Release gpio lines before reconfiguring them. diff --git a/Documentation/block/00-INDEX b/Documentation/block/00-INDEX index a406286f6f3e..d111e3b23db0 100644 --- a/Documentation/block/00-INDEX +++ b/Documentation/block/00-INDEX @@ -1,7 +1,5 @@ 00-INDEX - This file -barrier.txt - - I/O Barriers biodoc.txt - Notes on the Generic Block Layer Rewrite in Linux 2.5 capability.txt @@ -16,3 +14,5 @@ stat.txt - Block layer statistics in /sys/block/<dev>/stat switching-sched.txt - Switching I/O schedulers at runtime +writeback_cache_control.txt + - Control of volatile write back caches diff --git a/Documentation/block/barrier.txt b/Documentation/block/barrier.txt deleted file mode 100644 index 2c2f24f634e4..000000000000 --- a/Documentation/block/barrier.txt +++ /dev/null @@ -1,261 +0,0 @@ -I/O Barriers -============ -Tejun Heo <htejun@gmail.com>, July 22 2005 - -I/O barrier requests are used to guarantee ordering around the barrier -requests. Unless you're crazy enough to use disk drives for -implementing synchronization constructs (wow, sounds interesting...), -the ordering is meaningful only for write requests for things like -journal checkpoints. All requests queued before a barrier request -must be finished (made it to the physical medium) before the barrier -request is started, and all requests queued after the barrier request -must be started only after the barrier request is finished (again, -made it to the physical medium). - -In other words, I/O barrier requests have the following two properties. - -1. Request ordering - -Requests cannot pass the barrier request. Preceding requests are -processed before the barrier and following requests after. - -Depending on what features a drive supports, this can be done in one -of the following three ways. - -i. For devices which have queue depth greater than 1 (TCQ devices) and -support ordered tags, block layer can just issue the barrier as an -ordered request and the lower level driver, controller and drive -itself are responsible for making sure that the ordering constraint is -met. Most modern SCSI controllers/drives should support this. - -NOTE: SCSI ordered tag isn't currently used due to limitation in the - SCSI midlayer, see the following random notes section. - -ii. For devices which have queue depth greater than 1 but don't -support ordered tags, block layer ensures that the requests preceding -a barrier request finishes before issuing the barrier request. Also, -it defers requests following the barrier until the barrier request is -finished. Older SCSI controllers/drives and SATA drives fall in this -category. - -iii. Devices which have queue depth of 1. This is a degenerate case -of ii. Just keeping issue order suffices. Ancient SCSI -controllers/drives and IDE drives are in this category. - -2. Forced flushing to physical medium - -Again, if you're not gonna do synchronization with disk drives (dang, -it sounds even more appealing now!), the reason you use I/O barriers -is mainly to protect filesystem integrity when power failure or some -other events abruptly stop the drive from operating and possibly make -the drive lose data in its cache. So, I/O barriers need to guarantee -that requests actually get written to non-volatile medium in order. - -There are four cases, - -i. No write-back cache. Keeping requests ordered is enough. - -ii. Write-back cache but no flush operation. There's no way to -guarantee physical-medium commit order. This kind of devices can't to -I/O barriers. - -iii. Write-back cache and flush operation but no FUA (forced unit -access). We need two cache flushes - before and after the barrier -request. - -iv. Write-back cache, flush operation and FUA. We still need one -flush to make sure requests preceding a barrier are written to medium, -but post-barrier flush can be avoided by using FUA write on the -barrier itself. - - -How to support barrier requests in drivers ------------------------------------------- - -All barrier handling is done inside block layer proper. All low level -drivers have to are implementing its prepare_flush_fn and using one -the following two functions to indicate what barrier type it supports -and how to prepare flush requests. Note that the term 'ordered' is -used to indicate the whole sequence of performing barrier requests -including draining and flushing. - -typedef void (prepare_flush_fn)(struct request_queue *q, struct request *rq); - -int blk_queue_ordered(struct request_queue *q, unsigned ordered, - prepare_flush_fn *prepare_flush_fn); - -@q : the queue in question -@ordered : the ordered mode the driver/device supports -@prepare_flush_fn : this function should prepare @rq such that it - flushes cache to physical medium when executed - -For example, SCSI disk driver's prepare_flush_fn looks like the -following. - -static void sd_prepare_flush(struct request_queue *q, struct request *rq) -{ - memset(rq->cmd, 0, sizeof(rq->cmd)); - rq->cmd_type = REQ_TYPE_BLOCK_PC; - rq->timeout = SD_TIMEOUT; - rq->cmd[0] = SYNCHRONIZE_CACHE; - rq->cmd_len = 10; -} - -The following seven ordered modes are supported. The following table -shows which mode should be used depending on what features a -device/driver supports. In the leftmost column of table, -QUEUE_ORDERED_ prefix is omitted from the mode names to save space. - -The table is followed by description of each mode. Note that in the -descriptions of QUEUE_ORDERED_DRAIN*, '=>' is used whereas '->' is -used for QUEUE_ORDERED_TAG* descriptions. '=>' indicates that the -preceding step must be complete before proceeding to the next step. -'->' indicates that the next step can start as soon as the previous -step is issued. - - write-back cache ordered tag flush FUA ------------------------------------------------------------------------ -NONE yes/no N/A no N/A -DRAIN no no N/A N/A -DRAIN_FLUSH yes no yes no -DRAIN_FUA yes no yes yes -TAG no yes N/A N/A -TAG_FLUSH yes yes yes no -TAG_FUA yes yes yes yes - - -QUEUE_ORDERED_NONE - I/O barriers are not needed and/or supported. - - Sequence: N/A - -QUEUE_ORDERED_DRAIN - Requests are ordered by draining the request queue and cache - flushing isn't needed. - - Sequence: drain => barrier - -QUEUE_ORDERED_DRAIN_FLUSH - Requests are ordered by draining the request queue and both - pre-barrier and post-barrier cache flushings are needed. - - Sequence: drain => preflush => barrier => postflush - -QUEUE_ORDERED_DRAIN_FUA - Requests are ordered by draining the request queue and - pre-barrier cache flushing is needed. By using FUA on barrier - request, post-barrier flushing can be skipped. - - Sequence: drain => preflush => barrier - -QUEUE_ORDERED_TAG - Requests are ordered by ordered tag and cache flushing isn't - needed. - - Sequence: barrier - -QUEUE_ORDERED_TAG_FLUSH - Requests are ordered by ordered tag and both pre-barrier and - post-barrier cache flushings are needed. - - Sequence: preflush -> barrier -> postflush - -QUEUE_ORDERED_TAG_FUA - Requests are ordered by ordered tag and pre-barrier cache - flushing is needed. By using FUA on barrier request, - post-barrier flushing can be skipped. - - Sequence: preflush -> barrier - - -Random notes/caveats --------------------- - -* SCSI layer currently can't use TAG ordering even if the drive, -controller and driver support it. The problem is that SCSI midlayer -request dispatch function is not atomic. It releases queue lock and -switch to SCSI host lock during issue and it's possible and likely to -happen in time that requests change their relative positions. Once -this problem is solved, TAG ordering can be enabled. - -* Currently, no matter which ordered mode is used, there can be only -one barrier request in progress. All I/O barriers are held off by -block layer until the previous I/O barrier is complete. This doesn't -make any difference for DRAIN ordered devices, but, for TAG ordered -devices with very high command latency, passing multiple I/O barriers -to low level *might* be helpful if they are very frequent. Well, this -certainly is a non-issue. I'm writing this just to make clear that no -two I/O barrier is ever passed to low-level driver. - -* Completion order. Requests in ordered sequence are issued in order -but not required to finish in order. Barrier implementation can -handle out-of-order completion of ordered sequence. IOW, the requests -MUST be processed in order but the hardware/software completion paths -are allowed to reorder completion notifications - eg. current SCSI -midlayer doesn't preserve completion order during error handling. - -* Requeueing order. Low-level drivers are free to requeue any request -after they removed it from the request queue with -blkdev_dequeue_request(). As barrier sequence should be kept in order -when requeued, generic elevator code takes care of putting requests in -order around barrier. See blk_ordered_req_seq() and -ELEVATOR_INSERT_REQUEUE handling in __elv_add_request() for details. - -Note that block drivers must not requeue preceding requests while -completing latter requests in an ordered sequence. Currently, no -error checking is done against this. - -* Error handling. Currently, block layer will report error to upper -layer if any of requests in an ordered sequence fails. Unfortunately, -this doesn't seem to be enough. Look at the following request flow. -QUEUE_ORDERED_TAG_FLUSH is in use. - - [0] [1] [2] [3] [pre] [barrier] [post] < [4] [5] [6] ... > - still in elevator - -Let's say request [2], [3] are write requests to update file system -metadata (journal or whatever) and [barrier] is used to mark that -those updates are valid. Consider the following sequence. - - i. Requests [0] ~ [post] leaves the request queue and enters - low-level driver. - ii. After a while, unfortunately, something goes wrong and the - drive fails [2]. Note that any of [0], [1] and [3] could have - completed by this time, but [pre] couldn't have been finished - as the drive must process it in order and it failed before - processing that command. - iii. Error handling kicks in and determines that the error is - unrecoverable and fails [2], and resumes operation. - iv. [pre] [barrier] [post] gets processed. - v. *BOOM* power fails - -The problem here is that the barrier request is *supposed* to indicate -that filesystem update requests [2] and [3] made it safely to the -physical medium and, if the machine crashes after the barrier is -written, filesystem recovery code can depend on that. Sadly, that -isn't true in this case anymore. IOW, the success of a I/O barrier -should also be dependent on success of some of the preceding requests, -where only upper layer (filesystem) knows what 'some' is. - -This can be solved by implementing a way to tell the block layer which -requests affect the success of the following barrier request and -making lower lever drivers to resume operation on error only after -block layer tells it to do so. - -As the probability of this happening is very low and the drive should -be faulty, implementing the fix is probably an overkill. But, still, -it's there. - -* In previous drafts of barrier implementation, there was fallback -mechanism such that, if FUA or ordered TAG fails, less fancy ordered -mode can be selected and the failed barrier request is retried -automatically. The rationale for this feature was that as FUA is -pretty new in ATA world and ordered tag was never used widely, there -could be devices which report to support those features but choke when -actually given such requests. - - This was removed for two reasons 1. it's an overkill 2. it's -impossible to implement properly when TAG ordering is used as low -level drivers resume after an error automatically. If it's ever -needed adding it back and modifying low level drivers accordingly -shouldn't be difficult. diff --git a/Documentation/block/writeback_cache_control.txt b/Documentation/block/writeback_cache_control.txt new file mode 100644 index 000000000000..83407d36630a --- /dev/null +++ b/Documentation/block/writeback_cache_control.txt @@ -0,0 +1,86 @@ + +Explicit volatile write back cache control +===================================== + +Introduction +------------ + +Many storage devices, especially in the consumer market, come with volatile +write back caches. That means the devices signal I/O completion to the +operating system before data actually has hit the non-volatile storage. This +behavior obviously speeds up various workloads, but it means the operating +system needs to force data out to the non-volatile storage when it performs +a data integrity operation like fsync, sync or an unmount. + +The Linux block layer provides two simple mechanisms that let filesystems +control the caching behavior of the storage device. These mechanisms are +a forced cache flush, and the Force Unit Access (FUA) flag for requests. + + +Explicit cache flushes +---------------------- + +The REQ_FLUSH flag can be OR ed into the r/w flags of a bio submitted from +the filesystem and will make sure the volatile cache of the storage device +has been flushed before the actual I/O operation is started. This explicitly +guarantees that previously completed write requests are on non-volatile +storage before the flagged bio starts. In addition the REQ_FLUSH flag can be +set on an otherwise empty bio structure, which causes only an explicit cache +flush without any dependent I/O. It is recommend to use +the blkdev_issue_flush() helper for a pure cache flush. + + +Forced Unit Access +----------------- + +The REQ_FUA flag can be OR ed into the r/w flags of a bio submitted from the +filesystem and will make sure that I/O completion for this request is only +signaled after the data has been committed to non-volatile storage. + + +Implementation details for filesystems +-------------------------------------- + +Filesystems can simply set the REQ_FLUSH and REQ_FUA bits and do not have to +worry if the underlying devices need any explicit cache flushing and how +the Forced Unit Access is implemented. The REQ_FLUSH and REQ_FUA flags +may both be set on a single bio. + + +Implementation details for make_request_fn based block drivers +-------------------------------------------------------------- + +These drivers will always see the REQ_FLUSH and REQ_FUA bits as they sit +directly below the submit_bio interface. For remapping drivers the REQ_FUA +bits need to be propagated to underlying devices, and a global flush needs +to be implemented for bios with the REQ_FLUSH bit set. For real device +drivers that do not have a volatile cache the REQ_FLUSH and REQ_FUA bits +on non-empty bios can simply be ignored, and REQ_FLUSH requests without +data can be completed successfully without doing any work. Drivers for +devices with volatile caches need to implement the support for these +flags themselves without any help from the block layer. + + +Implementation details for request_fn based block drivers +-------------------------------------------------------------- + +For devices that do not support volatile write caches there is no driver +support required, the block layer completes empty REQ_FLUSH requests before +entering the driver and strips off the REQ_FLUSH and REQ_FUA bits from +requests that have a payload. For devices with volatile write caches the +driver needs to tell the block layer that it supports flushing caches by +doing: + + blk_queue_flush(sdkp->disk->queue, REQ_FLUSH); + +and handle empty REQ_FLUSH requests in its prep_fn/request_fn. Note that +REQ_FLUSH requests with a payload are automatically turned into a sequence +of an empty REQ_FLUSH request followed by the actual write by the block +layer. For devices that also support the FUA bit the block layer needs +to be told to pass through the REQ_FUA bit using: + + blk_queue_flush(sdkp->disk->queue, REQ_FLUSH | REQ_FUA); + +and the driver must handle write requests that have the REQ_FUA bit set +in prep_fn/request_fn. If the FUA bit is not natively supported the block +layer turns it into an empty REQ_FLUSH request after the actual write. diff --git a/Documentation/cgroups/blkio-controller.txt b/Documentation/cgroups/blkio-controller.txt index 6919d62591d9..d6da611f8f63 100644 --- a/Documentation/cgroups/blkio-controller.txt +++ b/Documentation/cgroups/blkio-controller.txt @@ -8,12 +8,17 @@ both at leaf nodes as well as at intermediate nodes in a storage hierarchy. Plan is to use the same cgroup based management interface for blkio controller and based on user options switch IO policies in the background. -In the first phase, this patchset implements proportional weight time based -division of disk policy. It is implemented in CFQ. Hence this policy takes -effect only on leaf nodes when CFQ is being used. +Currently two IO control policies are implemented. First one is proportional +weight time based division of disk policy. It is implemented in CFQ. Hence +this policy takes effect only on leaf nodes when CFQ is being used. The second +one is throttling policy which can be used to specify upper IO rate limits +on devices. This policy is implemented in generic block layer and can be +used on leaf nodes as well as higher level logical devices like device mapper. HOWTO ===== +Proportional Weight division of bandwidth +----------------------------------------- You can do a very simple testing of running two dd threads in two different cgroups. Here is what you can do. @@ -55,6 +60,35 @@ cgroups. Here is what you can do. group dispatched to the disk. We provide fairness in terms of disk time, so ideally io.disk_time of cgroups should be in proportion to the weight. +Throttling/Upper Limit policy +----------------------------- +- Enable Block IO controller + CONFIG_BLK_CGROUP=y + +- Enable throttling in block layer + CONFIG_BLK_DEV_THROTTLING=y + +- Mount blkio controller + mount -t cgroup -o blkio none /cgroup/blkio + +- Specify a bandwidth rate on particular device for root group. The format + for policy is "<major>:<minor> <byes_per_second>". + + echo "8:16 1048576" > /cgroup/blkio/blkio.read_bps_device + + Above will put a limit of 1MB/second on reads happening for root group + on device having major/minor number 8:16. + +- Run dd to read a file and see if rate is throttled to 1MB/s or not. + + # dd if=/mnt/common/zerofile of=/dev/null bs=4K count=1024 + # iflag=direct + 1024+0 records in + 1024+0 records out + 4194304 bytes (4.2 MB) copied, 4.0001 s, 1.0 MB/s + + Limits for writes can be put using blkio.write_bps_device file. + Various user visible config options =================================== CONFIG_BLK_CGROUP @@ -68,8 +102,13 @@ CONFIG_CFQ_GROUP_IOSCHED - Enables group scheduling in CFQ. Currently only 1 level of group creation is allowed. +CONFIG_BLK_DEV_THROTTLING + - Enable block device throttling support in block layer. + Details of cgroup files ======================= +Proportional weight policy files +-------------------------------- - blkio.weight - Specifies per cgroup weight. This is default weight of the group on all the devices until and unless overridden by per device rule. @@ -210,6 +249,67 @@ Details of cgroup files and minor number of the device and third field specifies the number of times a group was dequeued from a particular device. +Throttling/Upper limit policy files +----------------------------------- +- blkio.throttle.read_bps_device + - Specifies upper limit on READ rate from the device. IO rate is + specified in bytes per second. Rules are per deivce. Following is + the format. + + echo "<major>:<minor> <rate_bytes_per_second>" > /cgrp/blkio.read_bps_device + +- blkio.throttle.write_bps_device + - Specifies upper limit on WRITE rate to the device. IO rate is + specified in bytes per second. Rules are per deivce. Following is + the format. + + echo "<major>:<minor> <rate_bytes_per_second>" > /cgrp/blkio.write_bps_device + +- blkio.throttle.read_iops_device + - Specifies upper limit on READ rate from the device. IO rate is + specified in IO per second. Rules are per deivce. Following is + the format. + + echo "<major>:<minor> <rate_io_per_second>" > /cgrp/blkio.read_iops_device + +- blkio.throttle.write_iops_device + - Specifies upper limit on WRITE rate to the device. IO rate is + specified in io per second. Rules are per deivce. Following is + the format. + + echo "<major>:<minor> <rate_io_per_second>" > /cgrp/blkio.write_iops_device + +Note: If both BW and IOPS rules are specified for a device, then IO is + subjectd to both the constraints. + +- blkio.throttle.io_serviced + - Number of IOs (bio) completed to/from the disk by the group (as + seen by throttling policy). These are further divided by the type + of operation - read or write, sync or async. First two fields specify + the major and minor number of the device, third field specifies the + operation type and the fourth field specifies the number of IOs. + + blkio.io_serviced does accounting as seen by CFQ and counts are in + number of requests (struct request). On the other hand, + blkio.throttle.io_serviced counts number of IO in terms of number + of bios as seen by throttling policy. These bios can later be + merged by elevator and total number of requests completed can be + lesser. + +- blkio.throttle.io_service_bytes + - Number of bytes transferred to/from the disk by the group. These + are further divided by the type of operation - read or write, sync + or async. First two fields specify the major and minor number of the + device, third field specifies the operation type and the fourth field + specifies the number of bytes. + + These numbers should roughly be same as blkio.io_service_bytes as + updated by CFQ. The difference between two is that + blkio.io_service_bytes will not be updated if CFQ is not operating + on request queue. + +Common files among various policies +----------------------------------- - blkio.reset_stats - Writing an int to this file will result in resetting all the stats for that cgroup. diff --git a/Documentation/cputopology.txt b/Documentation/cputopology.txt index f1c5c4bccd3e..902d3151f527 100644 --- a/Documentation/cputopology.txt +++ b/Documentation/cputopology.txt @@ -14,25 +14,39 @@ to /proc/cpuinfo. identifier (rather than the kernel's). The actual value is architecture and platform dependent. -3) /sys/devices/system/cpu/cpuX/topology/thread_siblings: +3) /sys/devices/system/cpu/cpuX/topology/book_id: + + the book ID of cpuX. Typically it is the hardware platform's + identifier (rather than the kernel's). The actual value is + architecture and platform dependent. + +4) /sys/devices/system/cpu/cpuX/topology/thread_siblings: internel kernel map of cpuX's hardware threads within the same core as cpuX -4) /sys/devices/system/cpu/cpuX/topology/core_siblings: +5) /sys/devices/system/cpu/cpuX/topology/core_siblings: internal kernel map of cpuX's hardware threads within the same physical_package_id. +6) /sys/devices/system/cpu/cpuX/topology/book_siblings: + + internal kernel map of cpuX's hardware threads within the same + book_id. + To implement it in an architecture-neutral way, a new source file, -drivers/base/topology.c, is to export the 4 attributes. +drivers/base/topology.c, is to export the 4 or 6 attributes. The two book +related sysfs files will only be created if CONFIG_SCHED_BOOK is selected. For an architecture to support this feature, it must define some of these macros in include/asm-XXX/topology.h: #define topology_physical_package_id(cpu) #define topology_core_id(cpu) +#define topology_book_id(cpu) #define topology_thread_cpumask(cpu) #define topology_core_cpumask(cpu) +#define topology_book_cpumask(cpu) The type of **_id is int. The type of siblings is (const) struct cpumask *. @@ -45,6 +59,9 @@ not defined by include/asm-XXX/topology.h: 3) thread_siblings: just the given CPU 4) core_siblings: just the given CPU +For architectures that don't support books (CONFIG_SCHED_BOOK) there are no +default definitions for topology_book_id() and topology_book_cpumask(). + Additionally, CPU topology information is provided under /sys/devices/system/cpu and includes these files. The internal source for the output is in brackets ("[]"). diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt index 842aa9de84a6..5e2bc4ab897a 100644 --- a/Documentation/feature-removal-schedule.txt +++ b/Documentation/feature-removal-schedule.txt @@ -386,34 +386,6 @@ Who: Tejun Heo <tj@kernel.org> ---------------------------- -What: Support for VMware's guest paravirtuliazation technique [VMI] will be - dropped. -When: 2.6.37 or earlier. -Why: With the recent innovations in CPU hardware acceleration technologies - from Intel and AMD, VMware ran a few experiments to compare these - techniques to guest paravirtualization technique on VMware's platform. - These hardware assisted virtualization techniques have outperformed the - performance benefits provided by VMI in most of the workloads. VMware - expects that these hardware features will be ubiquitous in a couple of - years, as a result, VMware has started a phased retirement of this - feature from the hypervisor. We will be removing this feature from the - Kernel too. Right now we are targeting 2.6.37 but can retire earlier if - technical reasons (read opportunity to remove major chunk of pvops) - arise. - - Please note that VMI has always been an optimization and non-VMI kernels - still work fine on VMware's platform. - Latest versions of VMware's product which support VMI are, - Workstation 7.0 and VSphere 4.0 on ESX side, future maintainence - releases for these products will continue supporting VMI. - - For more details about VMI retirement take a look at this, - http://blogs.vmware.com/guestosguide/2009/09/vmi-retirement.html - -Who: Alok N Kataria <akataria@vmware.com> - ----------------------------- - What: Support for lcd_switch and display_get in asus-laptop driver When: March 2010 Why: These two features use non-standard interfaces. There are the diff --git a/Documentation/filesystems/ocfs2.txt b/Documentation/filesystems/ocfs2.txt index 1f7ae144f6d8..5393e6611691 100644 --- a/Documentation/filesystems/ocfs2.txt +++ b/Documentation/filesystems/ocfs2.txt @@ -87,3 +87,10 @@ dir_resv_level= (*) By default, directory reservations will scale with file reservations - users should rarely need to change this value. If allocation reservations are turned off, this option will have no effect. +coherency=full (*) Disallow concurrent O_DIRECT writes, cluster inode + lock will be taken to force other nodes drop cache, + therefore full cluster coherency is guaranteed even + for O_DIRECT writes. +coherency=buffered Allow concurrent O_DIRECT writes without EX lock among + nodes, which gains high performance at risk of getting + stale data on other nodes. diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 8dd7248508a9..02f21d9220ce 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -455,7 +455,7 @@ and is between 256 and 4096 characters. It is defined in the file [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2, pxa_timer,timer3,32k_counter,timer0_1 [AVR32] avr32 - [X86-32] pit,hpet,tsc,vmi-timer; + [X86-32] pit,hpet,tsc; scx200_hrt on Geode; cyclone on IBM x440 [MIPS] MIPS [PARISC] cr16 @@ -2153,6 +2153,11 @@ and is between 256 and 4096 characters. It is defined in the file Reserves a hole at the top of the kernel virtual address space. + reservelow= [X86] + Format: nn[K] + Set the amount of memory to reserve for BIOS at + the bottom of the address space. + reset_devices [KNL] Force drivers to reset the underlying device during initialization. @@ -2165,6 +2170,11 @@ and is between 256 and 4096 characters. It is defined in the file in <PAGE_SIZE> units (needed only for swap files). See Documentation/power/swsusp-and-swap-files.txt + hibernate= [HIBERNATION] + noresume Don't check if there's a hibernation image + present during boot. + nocompress Don't compress/decompress hibernation images. + retain_initrd [RAM] Keep initrd memory after extraction rhash_entries= [KNL,NET] @@ -2435,6 +2445,10 @@ and is between 256 and 4096 characters. It is defined in the file disables clocksource verification at runtime. Used to enable high-resolution timer mode on older hardware, and in virtualized environment. + [x86] noirqtime: Do not use TSC to do irq accounting. + Used to run time disable IRQ_TIME_ACCOUNTING on any + platforms where RDTSC is slow and this accounting + can add overhead. turbografx.map[2|3]= [HW,JOY] TurboGraFX parallel port interface diff --git a/Documentation/kprobes.txt b/Documentation/kprobes.txt index 1762b81fcdf2..741fe66d6eca 100644 --- a/Documentation/kprobes.txt +++ b/Documentation/kprobes.txt @@ -542,9 +542,11 @@ Kprobes does not use mutexes or allocate memory except during registration and unregistration. Probe handlers are run with preemption disabled. Depending on the -architecture, handlers may also run with interrupts disabled. In any -case, your handler should not yield the CPU (e.g., by attempting to -acquire a semaphore). +architecture and optimization state, handlers may also run with +interrupts disabled (e.g., kretprobe handlers and optimized kprobe +handlers run without interrupt disabled on x86/x86-64). In any case, +your handler should not yield the CPU (e.g., by attempting to acquire +a semaphore). Since a return probe is implemented by replacing the return address with the trampoline's address, stack backtraces and calls diff --git a/Documentation/lguest/lguest.c b/Documentation/lguest/lguest.c index 8a6a8c6d4980..dc73bc54cc4e 100644 --- a/Documentation/lguest/lguest.c +++ b/Documentation/lguest/lguest.c @@ -1640,15 +1640,6 @@ static void blk_request(struct virtqueue *vq) off = out->sector * 512; /* - * The block device implements "barriers", where the Guest indicates - * that it wants all previous writes to occur before this write. We - * don't have a way of asking our kernel to do a barrier, so we just - * synchronize all the data in the file. Pretty poor, no? - */ - if (out->type & VIRTIO_BLK_T_BARRIER) - fdatasync(vblk->fd); - - /* * In general the virtio block driver is allowed to try SCSI commands. * It'd be nice if we supported eject, for example, but we don't. */ @@ -1680,6 +1671,13 @@ static void blk_request(struct virtqueue *vq) /* Die, bad Guest, die. */ errx(1, "Write past end %llu+%u", off, ret); } + + wlen = sizeof(*in); + *in = (ret >= 0 ? VIRTIO_BLK_S_OK : VIRTIO_BLK_S_IOERR); + } else if (out->type & VIRTIO_BLK_T_FLUSH) { + /* Flush */ + ret = fdatasync(vblk->fd); + verbose("FLUSH fdatasync: %i\n", ret); wlen = sizeof(*in); *in = (ret >= 0 ? VIRTIO_BLK_S_OK : VIRTIO_BLK_S_IOERR); } else { @@ -1703,15 +1701,6 @@ static void blk_request(struct virtqueue *vq) } } - /* - * OK, so we noted that it was pretty poor to use an fdatasync as a - * barrier. But Christoph Hellwig points out that we need a sync - * *afterwards* as well: "Barriers specify no reordering to the front - * or the back." And Jens Axboe confirmed it, so here we are: - */ - if (out->type & VIRTIO_BLK_T_BARRIER) - fdatasync(vblk->fd); - /* Finished that request. */ add_used(vq, head, wlen); } @@ -1736,8 +1725,8 @@ static void setup_block_file(const char *filename) vblk->fd = open_or_die(filename, O_RDWR|O_LARGEFILE); vblk->len = lseek64(vblk->fd, 0, SEEK_END); - /* We support barriers. */ - add_feature(dev, VIRTIO_BLK_F_BARRIER); + /* We support FLUSH. */ + add_feature(dev, VIRTIO_BLK_F_FLUSH); /* Tell Guest how many sectors this device has. */ conf.capacity = cpu_to_le64(vblk->len / 512); diff --git a/Documentation/networking/e1000.txt b/Documentation/networking/e1000.txt index 2df71861e578..d9271e74e488 100644 --- a/Documentation/networking/e1000.txt +++ b/Documentation/networking/e1000.txt @@ -1,82 +1,35 @@ Linux* Base Driver for the Intel(R) PRO/1000 Family of Adapters =============================================================== -September 26, 2006 - +Intel Gigabit Linux driver. +Copyright(c) 1999 - 2010 Intel Corporation. Contents ======== -- In This Release - Identifying Your Adapter -- Building and Installation - Command Line Parameters - Speed and Duplex Configuration - Additional Configurations -- Known Issues - Support - -In This Release -=============== - -This file describes the Linux* Base Driver for the Intel(R) PRO/1000 Family -of Adapters. This driver includes support for Itanium(R)2-based systems. - -For questions related to hardware requirements, refer to the documentation -supplied with your Intel PRO/1000 adapter. All hardware requirements listed -apply to use with Linux. - -The following features are now available in supported kernels: - - Native VLANs - - Channel Bonding (teaming) - - SNMP - -Channel Bonding documentation can be found in the Linux kernel source: -/Documentation/networking/bonding.txt - -The driver information previously displayed in the /proc filesystem is not -supported in this release. Alternatively, you can use ethtool (version 1.6 -or later), lspci, and ifconfig to obtain the same information. - -Instructions on updating ethtool can be found in the section "Additional -Configurations" later in this document. - -NOTE: The Intel(R) 82562v 10/100 Network Connection only provides 10/100 -support. - - Identifying Your Adapter ======================== For more information on how to identify your adapter, go to the Adapter & Driver ID Guide at: - http://support.intel.com/support/network/adapter/pro100/21397.htm + http://support.intel.com/support/go/network/adapter/idguide.htm For the latest Intel network drivers for Linux, refer to the following website. In the search field, enter your adapter name or type, or use the networking link on the left to search for your adapter: - http://downloadfinder.intel.com/scripts-df/support_intel.asp - + http://support.intel.com/support/go/network/adapter/home.htm Command Line Parameters ======================= -If the driver is built as a module, the following optional parameters -are used by entering them on the command line with the modprobe command -using this syntax: - - modprobe e1000 [<option>=<VAL1>,<VAL2>,...] - -For example, with two PRO/1000 PCI adapters, entering: - - modprobe e1000 TxDescriptors=80,128 - -loads the e1000 driver with 80 TX descriptors for the first adapter and -128 TX descriptors for the second adapter. - The default value for each parameter is generally the recommended setting, unless otherwise noted. @@ -89,10 +42,6 @@ NOTES: For more information about the AutoNeg, Duplex, and Speed parameters, see the application note at: http://www.intel.com/design/network/applnots/ap450.htm - A descriptor describes a data buffer and attributes related to - the data buffer. This information is accessed by the hardware. - - AutoNeg ------- (Supported only on adapters with copper connections) @@ -106,7 +55,6 @@ Duplex parameters must not be specified. NOTE: Refer to the Speed and Duplex section of this readme for more information on the AutoNeg parameter. - Duplex ------ (Supported only on adapters with copper connections) @@ -119,7 +67,6 @@ set to auto-negotiate, the board auto-detects the correct duplex. If the link partner is forced (either full or half), Duplex defaults to half- duplex. - FlowControl ----------- Valid Range: 0-3 (0=none, 1=Rx only, 2=Tx only, 3=Rx&Tx) @@ -128,16 +75,16 @@ Default Value: Reads flow control settings from the EEPROM This parameter controls the automatic generation(Tx) and response(Rx) to Ethernet PAUSE frames. - InterruptThrottleRate --------------------- (not supported on Intel(R) 82542, 82543 or 82544-based adapters) -Valid Range: 0,1,3,100-100000 (0=off, 1=dynamic, 3=dynamic conservative) +Valid Range: 0,1,3,4,100-100000 (0=off, 1=dynamic, 3=dynamic conservative, + 4=simplified balancing) Default Value: 3 The driver can limit the amount of interrupts per second that the adapter -will generate for incoming packets. It does this by writing a value to the -adapter that is based on the maximum amount of interrupts that the adapter +will generate for incoming packets. It does this by writing a value to the +adapter that is based on the maximum amount of interrupts that the adapter will generate per second. Setting InterruptThrottleRate to a value greater or equal to 100 @@ -146,37 +93,43 @@ per second, even if more packets have come in. This reduces interrupt load on the system and can lower CPU utilization under heavy load, but will increase latency as packets are not processed as quickly. -The default behaviour of the driver previously assumed a static -InterruptThrottleRate value of 8000, providing a good fallback value for -all traffic types,but lacking in small packet performance and latency. -The hardware can handle many more small packets per second however, and +The default behaviour of the driver previously assumed a static +InterruptThrottleRate value of 8000, providing a good fallback value for +all traffic types,but lacking in small packet performance and latency. +The hardware can handle many more small packets per second however, and for this reason an adaptive interrupt moderation algorithm was implemented. Since 7.3.x, the driver has two adaptive modes (setting 1 or 3) in which -it dynamically adjusts the InterruptThrottleRate value based on the traffic +it dynamically adjusts the InterruptThrottleRate value based on the traffic that it receives. After determining the type of incoming traffic in the last -timeframe, it will adjust the InterruptThrottleRate to an appropriate value +timeframe, it will adjust the InterruptThrottleRate to an appropriate value for that traffic. The algorithm classifies the incoming traffic every interval into -classes. Once the class is determined, the InterruptThrottleRate value is -adjusted to suit that traffic type the best. There are three classes defined: +classes. Once the class is determined, the InterruptThrottleRate value is +adjusted to suit that traffic type the best. There are three classes defined: "Bulk traffic", for large amounts of packets of normal size; "Low latency", for small amounts of traffic and/or a significant percentage of small -packets; and "Lowest latency", for almost completely small packets or +packets; and "Lowest latency", for almost completely small packets or minimal traffic. -In dynamic conservative mode, the InterruptThrottleRate value is set to 4000 -for traffic that falls in class "Bulk traffic". If traffic falls in the "Low -latency" or "Lowest latency" class, the InterruptThrottleRate is increased +In dynamic conservative mode, the InterruptThrottleRate value is set to 4000 +for traffic that falls in class "Bulk traffic". If traffic falls in the "Low +latency" or "Lowest latency" class, the InterruptThrottleRate is increased stepwise to 20000. This default mode is suitable for most applications. For situations where low latency is vital such as cluster or grid computing, the algorithm can reduce latency even more when InterruptThrottleRate is set to mode 1. In this mode, which operates -the same as mode 3, the InterruptThrottleRate will be increased stepwise to +the same as mode 3, the InterruptThrottleRate will be increased stepwise to 70000 for traffic in class "Lowest latency". +In simplified mode the interrupt rate is based on the ratio of Tx and +Rx traffic. If the bytes per second rate is approximately equal, the +interrupt rate will drop as low as 2000 interrupts per second. If the +traffic is mostly transmit or mostly receive, the interrupt rate could +be as high as 8000. + Setting InterruptThrottleRate to 0 turns off any interrupt moderation and may improve small packet latency, but is generally not suitable for bulk throughput traffic. @@ -212,8 +165,6 @@ NOTE: When e1000 is loaded with default settings and multiple adapters be platform-specific. If CPU utilization is not a concern, use RX_POLLING (NAPI) and default driver settings. - - RxDescriptors ------------- Valid Range: 80-256 for 82542 and 82543-based adapters @@ -225,15 +176,14 @@ by the driver. Increasing this value allows the driver to buffer more incoming packets, at the expense of increased system memory utilization. Each descriptor is 16 bytes. A receive buffer is also allocated for each -descriptor and can be either 2048, 4096, 8192, or 16384 bytes, depending +descriptor and can be either 2048, 4096, 8192, or 16384 bytes, depending on the MTU setting. The maximum MTU size is 16110. -NOTE: MTU designates the frame size. It only needs to be set for Jumbo - Frames. Depending on the available system resources, the request - for a higher number of receive descriptors may be denied. In this +NOTE: MTU designates the frame size. It only needs to be set for Jumbo + Frames. Depending on the available system resources, the request + for a higher number of receive descriptors may be denied. In this case, use a lower number. - RxIntDelay ---------- Valid Range: 0-65535 (0=off) @@ -254,7 +204,6 @@ CAUTION: When setting RxIntDelay to a value other than 0, adapters may restoring the network connection. To eliminate the potential for the hang ensure that RxIntDelay is set to 0. - RxAbsIntDelay ------------- (This parameter is supported only on 82540, 82545 and later adapters.) @@ -268,7 +217,6 @@ packet is received within the set amount of time. Proper tuning, along with RxIntDelay, may improve traffic throughput in specific network conditions. - Speed ----- (This parameter is supported only on adapters with copper connections.) @@ -280,7 +228,6 @@ Speed forces the line speed to the specified value in megabits per second partner is set to auto-negotiate, the board will auto-detect the correct speed. Duplex should also be set when Speed is set to either 10 or 100. - TxDescriptors ------------- Valid Range: 80-256 for 82542 and 82543-based adapters @@ -295,6 +242,36 @@ NOTE: Depending on the available system resources, the request for a higher number of transmit descriptors may be denied. In this case, use a lower number. +TxDescriptorStep +---------------- +Valid Range: 1 (use every Tx Descriptor) + 4 (use every 4th Tx Descriptor) + +Default Value: 1 (use every Tx Descriptor) + +On certain non-Intel architectures, it has been observed that intense TX +traffic bursts of short packets may result in an improper descriptor +writeback. If this occurs, the driver will report a "TX Timeout" and reset +the adapter, after which the transmit flow will restart, though data may +have stalled for as much as 10 seconds before it resumes. + +The improper writeback does not occur on the first descriptor in a system +memory cache-line, which is typically 32 bytes, or 4 descriptors long. + +Setting TxDescriptorStep to a value of 4 will ensure that all TX descriptors +are aligned to the start of a system memory cache line, and so this problem +will not occur. + +NOTES: Setting TxDescriptorStep to 4 effectively reduces the number of + TxDescriptors available for transmits to 1/4 of the normal allocation. + This has a possible negative performance impact, which may be + compensated for by allocating more descriptors using the TxDescriptors + module parameter. + + There are other conditions which may result in "TX Timeout", which will + not be resolved by the use of the TxDescriptorStep parameter. As the + issue addressed by this parameter has never been observed on Intel + Architecture platforms, it should not be used on Intel platforms. TxIntDelay ---------- @@ -307,7 +284,6 @@ efficiency if properly tuned for specific network traffic. If the system is reporting dropped transmits, this value may be set too high causing the driver to run out of available transmit descriptors. - TxAbsIntDelay ------------- (This parameter is supported only on 82540, 82545 and later adapters.) @@ -330,6 +306,35 @@ Default Value: 1 A value of '1' indicates that the driver should enable IP checksum offload for received packets (both UDP and TCP) to the adapter hardware. +Copybreak +--------- +Valid Range: 0-xxxxxxx (0=off) +Default Value: 256 +Usage: insmod e1000.ko copybreak=128 + +Driver copies all packets below or equaling this size to a fresh Rx +buffer before handing it up the stack. + +This parameter is different than other parameters, in that it is a +single (not 1,1,1 etc.) parameter applied to all driver instances and +it is also available during runtime at +/sys/module/e1000/parameters/copybreak + +SmartPowerDownEnable +-------------------- +Valid Range: 0-1 +Default Value: 0 (disabled) + +Allows PHY to turn off in lower power states. The user can turn off +this parameter in supported chipsets. + +KumeranLockLoss +--------------- +Valid Range: 0-1 +Default Value: 1 (enabled) + +This workaround skips resetting the PHY at shutdown for the initial +silicon releases of ICH8 systems. Speed and Duplex Configuration ============================== @@ -385,40 +390,9 @@ If the link partner is forced to a specific speed and duplex, then this parameter should not be used. Instead, use the Speed and Duplex parameters previously mentioned to force the adapter to the same speed and duplex. - Additional Configurations ========================= - Configuring the Driver on Different Distributions - ------------------------------------------------- - Configuring a network driver to load properly when the system is started - is distribution dependent. Typically, the configuration process involves - adding an alias line to /etc/modules.conf or /etc/modprobe.conf as well - as editing other system startup scripts and/or configuration files. Many - popular Linux distributions ship with tools to make these changes for you. - To learn the proper way to configure a network device for your system, - refer to your distribution documentation. If during this process you are - asked for the driver or module name, the name for the Linux Base Driver - for the Intel(R) PRO/1000 Family of Adapters is e1000. - - As an example, if you install the e1000 driver for two PRO/1000 adapters - (eth0 and eth1) and set the speed and duplex to 10full and 100half, add - the following to modules.conf or or modprobe.conf: - - alias eth0 e1000 - alias eth1 e1000 - options e1000 Speed=10,100 Duplex=2,1 - - Viewing Link Messages - --------------------- - Link messages will not be displayed to the console if the distribution is - restricting system messages. In order to see network driver link messages - on your console, set dmesg to eight by entering the following: - - dmesg -n 8 - - NOTE: This setting is not saved across reboots. - Jumbo Frames ------------ Jumbo Frames support is enabled by changing the MTU to a value larger than @@ -437,9 +411,11 @@ Additional Configurations setting in a different location. Notes: - - - To enable Jumbo Frames, increase the MTU size on the interface beyond - 1500. + Degradation in throughput performance may be observed in some Jumbo frames + environments. If this is observed, increasing the application's socket buffer + size and/or increasing the /proc/sys/net/ipv4/tcp_*mem entry values may help. + See the specific application manual and /usr/src/linux*/Documentation/ + networking/ip-sysctl.txt for more details. - The maximum MTU setting for Jumbo Frames is 16110. This value coincides with the maximum Jumbo Frames size of 16128. @@ -447,40 +423,11 @@ Additional Configurations - Using Jumbo Frames at 10 or 100 Mbps may result in poor performance or loss of link. - - Some Intel gigabit adapters that support Jumbo Frames have a frame size - limit of 9238 bytes, with a corresponding MTU size limit of 9216 bytes. - The adapters with this limitation are based on the Intel(R) 82571EB, - 82572EI, 82573L and 80003ES2LAN controller. These correspond to the - following product names: - Intel(R) PRO/1000 PT Server Adapter - Intel(R) PRO/1000 PT Desktop Adapter - Intel(R) PRO/1000 PT Network Connection - Intel(R) PRO/1000 PT Dual Port Server Adapter - Intel(R) PRO/1000 PT Dual Port Network Connection - Intel(R) PRO/1000 PF Server Adapter - Intel(R) PRO/1000 PF Network Connection - Intel(R) PRO/1000 PF Dual Port Server Adapter - Intel(R) PRO/1000 PB Server Connection - Intel(R) PRO/1000 PL Network Connection - Intel(R) PRO/1000 EB Network Connection with I/O Acceleration - Intel(R) PRO/1000 EB Backplane Connection with I/O Acceleration - Intel(R) PRO/1000 PT Quad Port Server Adapter - - Adapters based on the Intel(R) 82542 and 82573V/E controller do not support Jumbo Frames. These correspond to the following product names: Intel(R) PRO/1000 Gigabit Server Adapter Intel(R) PRO/1000 PM Network Connection - - The following adapters do not support Jumbo Frames: - Intel(R) 82562V 10/100 Network Connection - Intel(R) 82566DM Gigabit Network Connection - Intel(R) 82566DC Gigabit Network Connection - Intel(R) 82566MM Gigabit Network Connection - Intel(R) 82566MC Gigabit Network Connection - Intel(R) 82562GT 10/100 Network Connection - Intel(R) 82562G 10/100 Network Connection - - Ethtool ------- The driver utilizes the ethtool interface for driver configuration and @@ -490,142 +437,14 @@ Additional Configurations The latest release of ethtool can be found from http://sourceforge.net/projects/gkernel. - NOTE: Ethtool 1.6 only supports a limited set of ethtool options. Support - for a more complete ethtool feature set can be enabled by upgrading - ethtool to ethtool-1.8.1. - Enabling Wake on LAN* (WoL) --------------------------- - WoL is configured through the Ethtool* utility. Ethtool is included with - all versions of Red Hat after Red Hat 7.2. For other Linux distributions, - download and install Ethtool from the following website: - http://sourceforge.net/projects/gkernel. - - For instructions on enabling WoL with Ethtool, refer to the website listed - above. + WoL is configured through the Ethtool* utility. WoL will be enabled on the system during the next shut down or reboot. For this driver version, in order to enable WoL, the e1000 driver must be loaded when shutting down or rebooting the system. - Wake On LAN is only supported on port A for the following devices: - Intel(R) PRO/1000 PT Dual Port Network Connection - Intel(R) PRO/1000 PT Dual Port Server Connection - Intel(R) PRO/1000 PT Dual Port Server Adapter - Intel(R) PRO/1000 PF Dual Port Server Adapter - Intel(R) PRO/1000 PT Quad Port Server Adapter - - NAPI - ---- - NAPI (Rx polling mode) is enabled in the e1000 driver. - - See www.cyberus.ca/~hadi/usenix-paper.tgz for more information on NAPI. - - -Known Issues -============ - -Dropped Receive Packets on Half-duplex 10/100 Networks ------------------------------------------------------- -If you have an Intel PCI Express adapter running at 10mbps or 100mbps, half- -duplex, you may observe occasional dropped receive packets. There are no -workarounds for this problem in this network configuration. The network must -be updated to operate in full-duplex, and/or 1000mbps only. - -Jumbo Frames System Requirement -------------------------------- -Memory allocation failures have been observed on Linux systems with 64 MB -of RAM or less that are running Jumbo Frames. If you are using Jumbo -Frames, your system may require more than the advertised minimum -requirement of 64 MB of system memory. - -Performance Degradation with Jumbo Frames ------------------------------------------ -Degradation in throughput performance may be observed in some Jumbo frames -environments. If this is observed, increasing the application's socket -buffer size and/or increasing the /proc/sys/net/ipv4/tcp_*mem entry values -may help. See the specific application manual and -/usr/src/linux*/Documentation/ -networking/ip-sysctl.txt for more details. - -Jumbo Frames on Foundry BigIron 8000 switch -------------------------------------------- -There is a known issue using Jumbo frames when connected to a Foundry -BigIron 8000 switch. This is a 3rd party limitation. If you experience -loss of packets, lower the MTU size. - -Allocating Rx Buffers when Using Jumbo Frames ---------------------------------------------- -Allocating Rx buffers when using Jumbo Frames on 2.6.x kernels may fail if -the available memory is heavily fragmented. This issue may be seen with PCI-X -adapters or with packet split disabled. This can be reduced or eliminated -by changing the amount of available memory for receive buffer allocation, by -increasing /proc/sys/vm/min_free_kbytes. - -Multiple Interfaces on Same Ethernet Broadcast Network ------------------------------------------------------- -Due to the default ARP behavior on Linux, it is not possible to have -one system on two IP networks in the same Ethernet broadcast domain -(non-partitioned switch) behave as expected. All Ethernet interfaces -will respond to IP traffic for any IP address assigned to the system. -This results in unbalanced receive traffic. - -If you have multiple interfaces in a server, either turn on ARP -filtering by entering: - - echo 1 > /proc/sys/net/ipv4/conf/all/arp_filter -(this only works if your kernel's version is higher than 2.4.5), - -NOTE: This setting is not saved across reboots. The configuration -change can be made permanent by adding the line: - net.ipv4.conf.all.arp_filter = 1 -to the file /etc/sysctl.conf - - or, - -install the interfaces in separate broadcast domains (either in -different switches or in a switch partitioned to VLANs). - -82541/82547 can't link or are slow to link with some link partners ------------------------------------------------------------------ -There is a known compatibility issue with 82541/82547 and some -low-end switches where the link will not be established, or will -be slow to establish. In particular, these switches are known to -be incompatible with 82541/82547: - - Planex FXG-08TE - I-O Data ETG-SH8 - -To workaround this issue, the driver can be compiled with an override -of the PHY's master/slave setting. Forcing master or forcing slave -mode will improve time-to-link. - - # make CFLAGS_EXTRA=-DE1000_MASTER_SLAVE=<n> - -Where <n> is: - - 0 = Hardware default - 1 = Master mode - 2 = Slave mode - 3 = Auto master/slave - -Disable rx flow control with ethtool ------------------------------------- -In order to disable receive flow control using ethtool, you must turn -off auto-negotiation on the same command line. - -For example: - - ethtool -A eth? autoneg off rx off - -Unplugging network cable while ethtool -p is running ----------------------------------------------------- -In kernel versions 2.5.50 and later (including 2.6 kernel), unplugging -the network cable while ethtool -p is running will cause the system to -become unresponsive to keyboard commands, except for control-alt-delete. -Restarting the system appears to be the only remedy. - - Support ======= diff --git a/Documentation/networking/e1000e.txt b/Documentation/networking/e1000e.txt new file mode 100644 index 000000000000..6aa048badf32 --- /dev/null +++ b/Documentation/networking/e1000e.txt @@ -0,0 +1,302 @@ +Linux* Driver for Intel(R) Network Connection +=============================================================== + +Intel Gigabit Linux driver. +Copyright(c) 1999 - 2010 Intel Corporation. + +Contents +======== + +- Identifying Your Adapter +- Command Line Parameters +- Additional Configurations +- Support + +Identifying Your Adapter +======================== + +The e1000e driver supports all PCI Express Intel(R) Gigabit Network +Connections, except those that are 82575, 82576 and 82580-based*. + +* NOTE: The Intel(R) PRO/1000 P Dual Port Server Adapter is supported by + the e1000 driver, not the e1000e driver due to the 82546 part being used + behind a PCI Express bridge. + +For more information on how to identify your adapter, go to the Adapter & +Driver ID Guide at: + + http://support.intel.com/support/go/network/adapter/idguide.htm + +For the latest Intel network drivers for Linux, refer to the following +website. In the search field, enter your adapter name or type, or use the +networking link on the left to search for your adapter: + + http://support.intel.com/support/go/network/adapter/home.htm + +Command Line Parameters +======================= + +The default value for each parameter is generally the recommended setting, +unless otherwise noted. + +NOTES: For more information about the InterruptThrottleRate, + RxIntDelay, TxIntDelay, RxAbsIntDelay, and TxAbsIntDelay + parameters, see the application note at: + http://www.intel.com/design/network/applnots/ap450.htm + +InterruptThrottleRate +--------------------- +Valid Range: 0,1,3,4,100-100000 (0=off, 1=dynamic, 3=dynamic conservative, + 4=simplified balancing) +Default Value: 3 + +The driver can limit the amount of interrupts per second that the adapter +will generate for incoming packets. It does this by writing a value to the +adapter that is based on the maximum amount of interrupts that the adapter +will generate per second. + +Setting InterruptThrottleRate to a value greater or equal to 100 +will program the adapter to send out a maximum of that many interrupts +per second, even if more packets have come in. This reduces interrupt +load on the system and can lower CPU utilization under heavy load, +but will increase latency as packets are not processed as quickly. + +The driver has two adaptive modes (setting 1 or 3) in which +it dynamically adjusts the InterruptThrottleRate value based on the traffic +that it receives. After determining the type of incoming traffic in the last +timeframe, it will adjust the InterruptThrottleRate to an appropriate value +for that traffic. + +The algorithm classifies the incoming traffic every interval into +classes. Once the class is determined, the InterruptThrottleRate value is +adjusted to suit that traffic type the best. There are three classes defined: +"Bulk traffic", for large amounts of packets of normal size; "Low latency", +for small amounts of traffic and/or a significant percentage of small +packets; and "Lowest latency", for almost completely small packets or +minimal traffic. + +In dynamic conservative mode, the InterruptThrottleRate value is set to 4000 +for traffic that falls in class "Bulk traffic". If traffic falls in the "Low +latency" or "Lowest latency" class, the InterruptThrottleRate is increased +stepwise to 20000. This default mode is suitable for most applications. + +For situations where low latency is vital such as cluster or +grid computing, the algorithm can reduce latency even more when +InterruptThrottleRate is set to mode 1. In this mode, which operates +the same as mode 3, the InterruptThrottleRate will be increased stepwise to +70000 for traffic in class "Lowest latency". + +In simplified mode the interrupt rate is based on the ratio of Tx and +Rx traffic. If the bytes per second rate is approximately equal the +interrupt rate will drop as low as 2000 interrupts per second. If the +traffic is mostly transmit or mostly receive, the interrupt rate could +be as high as 8000. + +Setting InterruptThrottleRate to 0 turns off any interrupt moderation +and may improve small packet latency, but is generally not suitable +for bulk throughput traffic. + +NOTE: InterruptThrottleRate takes precedence over the TxAbsIntDelay and + RxAbsIntDelay parameters. In other words, minimizing the receive + and/or transmit absolute delays does not force the controller to + generate more interrupts than what the Interrupt Throttle Rate + allows. + +NOTE: When e1000e is loaded with default settings and multiple adapters + are in use simultaneously, the CPU utilization may increase non- + linearly. In order to limit the CPU utilization without impacting + the overall throughput, we recommend that you load the driver as + follows: + + modprobe e1000e InterruptThrottleRate=3000,3000,3000 + + This sets the InterruptThrottleRate to 3000 interrupts/sec for + the first, second, and third instances of the driver. The range + of 2000 to 3000 interrupts per second works on a majority of + systems and is a good starting point, but the optimal value will + be platform-specific. If CPU utilization is not a concern, use + RX_POLLING (NAPI) and default driver settings. + +RxIntDelay +---------- +Valid Range: 0-65535 (0=off) +Default Value: 0 + +This value delays the generation of receive interrupts in units of 1.024 +microseconds. Receive interrupt reduction can improve CPU efficiency if +properly tuned for specific network traffic. Increasing this value adds +extra latency to frame reception and can end up decreasing the throughput +of TCP traffic. If the system is reporting dropped receives, this value +may be set too high, causing the driver to run out of available receive +descriptors. + +CAUTION: When setting RxIntDelay to a value other than 0, adapters may + hang (stop transmitting) under certain network conditions. If + this occurs a NETDEV WATCHDOG message is logged in the system + event log. In addition, the controller is automatically reset, + restoring the network connection. To eliminate the potential + for the hang ensure that RxIntDelay is set to 0. + +RxAbsIntDelay +------------- +Valid Range: 0-65535 (0=off) +Default Value: 8 + +This value, in units of 1.024 microseconds, limits the delay in which a +receive interrupt is generated. Useful only if RxIntDelay is non-zero, +this value ensures that an interrupt is generated after the initial +packet is received within the set amount of time. Proper tuning, +along with RxIntDelay, may improve traffic throughput in specific network +conditions. + +TxIntDelay +---------- +Valid Range: 0-65535 (0=off) +Default Value: 8 + +This value delays the generation of transmit interrupts in units of +1.024 microseconds. Transmit interrupt reduction can improve CPU +efficiency if properly tuned for specific network traffic. If the +system is reporting dropped transmits, this value may be set too high +causing the driver to run out of available transmit descriptors. + +TxAbsIntDelay +------------- +Valid Range: 0-65535 (0=off) +Default Value: 32 + +This value, in units of 1.024 microseconds, limits the delay in which a +transmit interrupt is generated. Useful only if TxIntDelay is non-zero, +this value ensures that an interrupt is generated after the initial +packet is sent on the wire within the set amount of time. Proper tuning, +along with TxIntDelay, may improve traffic throughput in specific +network conditions. + +Copybreak +--------- +Valid Range: 0-xxxxxxx (0=off) +Default Value: 256 + +Driver copies all packets below or equaling this size to a fresh Rx +buffer before handing it up the stack. + +This parameter is different than other parameters, in that it is a +single (not 1,1,1 etc.) parameter applied to all driver instances and +it is also available during runtime at +/sys/module/e1000e/parameters/copybreak + +SmartPowerDownEnable +-------------------- +Valid Range: 0-1 +Default Value: 0 (disabled) + +Allows PHY to turn off in lower power states. The user can set this parameter +in supported chipsets. + +KumeranLockLoss +--------------- +Valid Range: 0-1 +Default Value: 1 (enabled) + +This workaround skips resetting the PHY at shutdown for the initial +silicon releases of ICH8 systems. + +IntMode +------- +Valid Range: 0-2 (0=legacy, 1=MSI, 2=MSI-X) +Default Value: 2 + +Allows changing the interrupt mode at module load time, without requiring a +recompile. If the driver load fails to enable a specific interrupt mode, the +driver will try other interrupt modes, from least to most compatible. The +interrupt order is MSI-X, MSI, Legacy. If specifying MSI (IntMode=1) +interrupts, only MSI and Legacy will be attempted. + +CrcStripping +------------ +Valid Range: 0-1 +Default Value: 1 (enabled) + +Strip the CRC from received packets before sending up the network stack. If +you have a machine with a BMC enabled but cannot receive IPMI traffic after +loading or enabling the driver, try disabling this feature. + +WriteProtectNVM +--------------- +Valid Range: 0-1 +Default Value: 1 (enabled) + +Set the hardware to ignore all write/erase cycles to the GbE region in the +ICHx NVM (non-volatile memory). This feature can be disabled by the +WriteProtectNVM module parameter (enabled by default) only after a hardware +reset, but the machine must be power cycled before trying to enable writes. + +Note: the kernel boot option iomem=relaxed may need to be set if the kernel +config option CONFIG_STRICT_DEVMEM=y, if the root user wants to write the +NVM from user space via ethtool. + +Additional Configurations +========================= + + Jumbo Frames + ------------ + Jumbo Frames support is enabled by changing the MTU to a value larger than + the default of 1500. Use the ifconfig command to increase the MTU size. + For example: + + ifconfig eth<x> mtu 9000 up + + This setting is not saved across reboots. + + Notes: + + - The maximum MTU setting for Jumbo Frames is 9216. This value coincides + with the maximum Jumbo Frames size of 9234 bytes. + + - Using Jumbo Frames at 10 or 100 Mbps is not supported and may result in + poor performance or loss of link. + + - Some adapters limit Jumbo Frames sized packets to a maximum of + 4096 bytes and some adapters do not support Jumbo Frames. + + + Ethtool + ------- + The driver utilizes the ethtool interface for driver configuration and + diagnostics, as well as displaying statistical information. We + strongly recommend downloading the latest version of Ethtool at: + + http://sourceforge.net/projects/gkernel. + + Speed and Duplex + ---------------- + Speed and Duplex are configured through the Ethtool* utility. For + instructions, refer to the Ethtool man page. + + Enabling Wake on LAN* (WoL) + --------------------------- + WoL is configured through the Ethtool* utility. For instructions on + enabling WoL with Ethtool, refer to the Ethtool man page. + + WoL will be enabled on the system during the next shut down or reboot. + For this driver version, in order to enable WoL, the e1000e driver must be + loaded when shutting down or rebooting the system. + + In most cases Wake On LAN is only supported on port A for multiple port + adapters. To verify if a port supports Wake on LAN run ethtool eth<X>. + + +Support +======= + +For general information, go to the Intel support website at: + + www.intel.com/support/ + +or the Intel Wired Networking project hosted by Sourceforge at: + + http://sourceforge.net/projects/e1000 + +If an issue is identified with the released source code on the supported +kernel with a supported adapter, email the specific information related +to the issue to e1000-devel@lists.sf.net diff --git a/Documentation/networking/ixgbevf.txt b/Documentation/networking/ixgbevf.txt index 19015de6725f..21dd5d15b6b4 100755..100644 --- a/Documentation/networking/ixgbevf.txt +++ b/Documentation/networking/ixgbevf.txt @@ -1,19 +1,16 @@ Linux* Base Driver for Intel(R) Network Connection ================================================== -November 24, 2009 +Intel Gigabit Linux driver. +Copyright(c) 1999 - 2010 Intel Corporation. Contents ======== -- In This Release - Identifying Your Adapter - Known Issues/Troubleshooting - Support -In This Release -=============== - This file describes the ixgbevf Linux* Base Driver for Intel Network Connection. @@ -33,7 +30,7 @@ Identifying Your Adapter For more information on how to identify your adapter, go to the Adapter & Driver ID Guide at: - http://support.intel.com/support/network/sb/CS-008441.htm + http://support.intel.com/support/go/network/adapter/idguide.htm Known Issues/Troubleshooting ============================ @@ -57,34 +54,3 @@ or the Intel Wired Networking project hosted by Sourceforge at: If an issue is identified with the released source code on the supported kernel with a supported adapter, email the specific information related to the issue to e1000-devel@lists.sf.net - -License -======= - -Intel 10 Gigabit Linux driver. -Copyright(c) 1999 - 2009 Intel Corporation. - -This program is free software; you can redistribute it and/or modify it -under the terms and conditions of the GNU General Public License, -version 2, as published by the Free Software Foundation. - -This program is distributed in the hope it will be useful, but WITHOUT -ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or -FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for -more details. - -You should have received a copy of the GNU General Public License along with -this program; if not, write to the Free Software Foundation, Inc., -51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA. - -The full GNU General Public License is included in this distribution in -the file called "COPYING". - -Trademarks -========== - -Intel, Itanium, and Pentium are trademarks or registered trademarks of -Intel Corporation or its subsidiaries in the United States and other -countries. - -* Other names and brands may be claimed as the property of others. diff --git a/Documentation/pcmcia/driver-changes.txt b/Documentation/pcmcia/driver-changes.txt index 26c0f9c00545..dd04361dd361 100644 --- a/Documentation/pcmcia/driver-changes.txt +++ b/Documentation/pcmcia/driver-changes.txt @@ -1,4 +1,29 @@ This file details changes in 2.6 which affect PCMCIA card driver authors: +* pcmcia_loop_config() and autoconfiguration (as of 2.6.36) + If struct pcmcia_device *p_dev->config_flags is set accordingly, + pcmcia_loop_config() now sets up certain configuration values + automatically, though the driver may still override the settings + in the callback function. The following autoconfiguration options + are provided at the moment: + CONF_AUTO_CHECK_VCC : check for matching Vcc + CONF_AUTO_SET_VPP : set Vpp + CONF_AUTO_AUDIO : auto-enable audio line, if required + CONF_AUTO_SET_IO : set ioport resources (->resource[0,1]) + CONF_AUTO_SET_IOMEM : set first iomem resource (->resource[2]) + +* pcmcia_request_configuration -> pcmcia_enable_device (as of 2.6.36) + pcmcia_request_configuration() got renamed to pcmcia_enable_device(), + as it mirrors pcmcia_disable_device(). Configuration settings are now + stored in struct pcmcia_device, e.g. in the fields config_flags, + config_index, config_base, vpp. + +* pcmcia_request_window changes (as of 2.6.36) + Instead of win_req_t, drivers are now requested to fill out + struct pcmcia_device *p_dev->resource[2,3,4,5] for up to four ioport + ranges. After a call to pcmcia_request_window(), the regions found there + are reserved and may be used immediately -- until pcmcia_release_window() + is called. + * pcmcia_request_io changes (as of 2.6.36) Instead of io_req_t, drivers are now requested to fill out struct pcmcia_device *p_dev->resource[0,1] for up to two ioport diff --git a/Documentation/power/00-INDEX b/Documentation/power/00-INDEX index fb742c213c9e..45e9d4a91284 100644 --- a/Documentation/power/00-INDEX +++ b/Documentation/power/00-INDEX @@ -14,6 +14,8 @@ interface.txt - Power management user interface in /sys/power notifiers.txt - Registering suspend notifiers in device drivers +opp.txt + - Operating Performance Point library pci.txt - How the PCI Subsystem Does Power Management pm_qos_interface.txt diff --git a/Documentation/power/interface.txt b/Documentation/power/interface.txt index e67211fe0ee2..c537834af005 100644 --- a/Documentation/power/interface.txt +++ b/Documentation/power/interface.txt @@ -57,7 +57,7 @@ smallest image possible. In particular, if "0" is written to this file, the suspend image will be as small as possible. Reading from this file will display the current image size limit, which -is set to 500 MB by default. +is set to 2/5 of available RAM by default. /sys/power/pm_trace controls the code which saves the last PM event point in the RTC across reboots, so that you can debug a machine that just hangs diff --git a/Documentation/power/opp.txt b/Documentation/power/opp.txt new file mode 100644 index 000000000000..44d87ad3cea9 --- /dev/null +++ b/Documentation/power/opp.txt @@ -0,0 +1,375 @@ +*=============* +* OPP Library * +*=============* + +(C) 2009-2010 Nishanth Menon <nm@ti.com>, Texas Instruments Incorporated + +Contents +-------- +1. Introduction +2. Initial OPP List Registration +3. OPP Search Functions +4. OPP Availability Control Functions +5. OPP Data Retrieval Functions +6. Cpufreq Table Generation +7. Data Structures + +1. Introduction +=============== +Complex SoCs of today consists of a multiple sub-modules working in conjunction. +In an operational system executing varied use cases, not all modules in the SoC +need to function at their highest performing frequency all the time. To +facilitate this, sub-modules in a SoC are grouped into domains, allowing some +domains to run at lower voltage and frequency while other domains are loaded +more. The set of discrete tuples consisting of frequency and voltage pairs that +the device will support per domain are called Operating Performance Points or +OPPs. + +OPP library provides a set of helper functions to organize and query the OPP +information. The library is located in drivers/base/power/opp.c and the header +is located in include/linux/opp.h. OPP library can be enabled by enabling +CONFIG_PM_OPP from power management menuconfig menu. OPP library depends on +CONFIG_PM as certain SoCs such as Texas Instrument's OMAP framework allows to +optionally boot at a certain OPP without needing cpufreq. + +Typical usage of the OPP library is as follows: +(users) -> registers a set of default OPPs -> (library) +SoC framework -> modifies on required cases certain OPPs -> OPP layer + -> queries to search/retrieve information -> + +OPP layer expects each domain to be represented by a unique device pointer. SoC +framework registers a set of initial OPPs per device with the OPP layer. This +list is expected to be an optimally small number typically around 5 per device. +This initial list contains a set of OPPs that the framework expects to be safely +enabled by default in the system. + +Note on OPP Availability: +------------------------ +As the system proceeds to operate, SoC framework may choose to make certain +OPPs available or not available on each device based on various external +factors. Example usage: Thermal management or other exceptional situations where +SoC framework might choose to disable a higher frequency OPP to safely continue +operations until that OPP could be re-enabled if possible. + +OPP library facilitates this concept in it's implementation. The following +operational functions operate only on available opps: +opp_find_freq_{ceil, floor}, opp_get_voltage, opp_get_freq, opp_get_opp_count +and opp_init_cpufreq_table + +opp_find_freq_exact is meant to be used to find the opp pointer which can then +be used for opp_enable/disable functions to make an opp available as required. + +WARNING: Users of OPP library should refresh their availability count using +get_opp_count if opp_enable/disable functions are invoked for a device, the +exact mechanism to trigger these or the notification mechanism to other +dependent subsystems such as cpufreq are left to the discretion of the SoC +specific framework which uses the OPP library. Similar care needs to be taken +care to refresh the cpufreq table in cases of these operations. + +WARNING on OPP List locking mechanism: +------------------------------------------------- +OPP library uses RCU for exclusivity. RCU allows the query functions to operate +in multiple contexts and this synchronization mechanism is optimal for a read +intensive operations on data structure as the OPP library caters to. + +To ensure that the data retrieved are sane, the users such as SoC framework +should ensure that the section of code operating on OPP queries are locked +using RCU read locks. The opp_find_freq_{exact,ceil,floor}, +opp_get_{voltage, freq, opp_count} fall into this category. + +opp_{add,enable,disable} are updaters which use mutex and implement it's own +RCU locking mechanisms. opp_init_cpufreq_table acts as an updater and uses +mutex to implment RCU updater strategy. These functions should *NOT* be called +under RCU locks and other contexts that prevent blocking functions in RCU or +mutex operations from working. + +2. Initial OPP List Registration +================================ +The SoC implementation calls opp_add function iteratively to add OPPs per +device. It is expected that the SoC framework will register the OPP entries +optimally- typical numbers range to be less than 5. The list generated by +registering the OPPs is maintained by OPP library throughout the device +operation. The SoC framework can subsequently control the availability of the +OPPs dynamically using the opp_enable / disable functions. + +opp_add - Add a new OPP for a specific domain represented by the device pointer. + The OPP is defined using the frequency and voltage. Once added, the OPP + is assumed to be available and control of it's availability can be done + with the opp_enable/disable functions. OPP library internally stores + and manages this information in the opp struct. This function may be + used by SoC framework to define a optimal list as per the demands of + SoC usage environment. + + WARNING: Do not use this function in interrupt context. + + Example: + soc_pm_init() + { + /* Do things */ + r = opp_add(mpu_dev, 1000000, 900000); + if (!r) { + pr_err("%s: unable to register mpu opp(%d)\n", r); + goto no_cpufreq; + } + /* Do cpufreq things */ + no_cpufreq: + /* Do remaining things */ + } + +3. OPP Search Functions +======================= +High level framework such as cpufreq operates on frequencies. To map the +frequency back to the corresponding OPP, OPP library provides handy functions +to search the OPP list that OPP library internally manages. These search +functions return the matching pointer representing the opp if a match is +found, else returns error. These errors are expected to be handled by standard +error checks such as IS_ERR() and appropriate actions taken by the caller. + +opp_find_freq_exact - Search for an OPP based on an *exact* frequency and + availability. This function is especially useful to enable an OPP which + is not available by default. + Example: In a case when SoC framework detects a situation where a + higher frequency could be made available, it can use this function to + find the OPP prior to call the opp_enable to actually make it available. + rcu_read_lock(); + opp = opp_find_freq_exact(dev, 1000000000, false); + rcu_read_unlock(); + /* dont operate on the pointer.. just do a sanity check.. */ + if (IS_ERR(opp)) { + pr_err("frequency not disabled!\n"); + /* trigger appropriate actions.. */ + } else { + opp_enable(dev,1000000000); + } + + NOTE: This is the only search function that operates on OPPs which are + not available. + +opp_find_freq_floor - Search for an available OPP which is *at most* the + provided frequency. This function is useful while searching for a lesser + match OR operating on OPP information in the order of decreasing + frequency. + Example: To find the highest opp for a device: + freq = ULONG_MAX; + rcu_read_lock(); + opp_find_freq_floor(dev, &freq); + rcu_read_unlock(); + +opp_find_freq_ceil - Search for an available OPP which is *at least* the + provided frequency. This function is useful while searching for a + higher match OR operating on OPP information in the order of increasing + frequency. + Example 1: To find the lowest opp for a device: + freq = 0; + rcu_read_lock(); + opp_find_freq_ceil(dev, &freq); + rcu_read_unlock(); + Example 2: A simplified implementation of a SoC cpufreq_driver->target: + soc_cpufreq_target(..) + { + /* Do stuff like policy checks etc. */ + /* Find the best frequency match for the req */ + rcu_read_lock(); + opp = opp_find_freq_ceil(dev, &freq); + rcu_read_unlock(); + if (!IS_ERR(opp)) + soc_switch_to_freq_voltage(freq); + else + /* do something when we cant satisfy the req */ + /* do other stuff */ + } + +4. OPP Availability Control Functions +===================================== +A default OPP list registered with the OPP library may not cater to all possible +situation. The OPP library provides a set of functions to modify the +availability of a OPP within the OPP list. This allows SoC frameworks to have +fine grained dynamic control of which sets of OPPs are operationally available. +These functions are intended to *temporarily* remove an OPP in conditions such +as thermal considerations (e.g. don't use OPPx until the temperature drops). + +WARNING: Do not use these functions in interrupt context. + +opp_enable - Make a OPP available for operation. + Example: Lets say that 1GHz OPP is to be made available only if the + SoC temperature is lower than a certain threshold. The SoC framework + implementation might choose to do something as follows: + if (cur_temp < temp_low_thresh) { + /* Enable 1GHz if it was disabled */ + rcu_read_lock(); + opp = opp_find_freq_exact(dev, 1000000000, false); + rcu_read_unlock(); + /* just error check */ + if (!IS_ERR(opp)) + ret = opp_enable(dev, 1000000000); + else + goto try_something_else; + } + +opp_disable - Make an OPP to be not available for operation + Example: Lets say that 1GHz OPP is to be disabled if the temperature + exceeds a threshold value. The SoC framework implementation might + choose to do something as follows: + if (cur_temp > temp_high_thresh) { + /* Disable 1GHz if it was enabled */ + rcu_read_lock(); + opp = opp_find_freq_exact(dev, 1000000000, true); + rcu_read_unlock(); + /* just error check */ + if (!IS_ERR(opp)) + ret = opp_disable(dev, 1000000000); + else + goto try_something_else; + } + +5. OPP Data Retrieval Functions +=============================== +Since OPP library abstracts away the OPP information, a set of functions to pull +information from the OPP structure is necessary. Once an OPP pointer is +retrieved using the search functions, the following functions can be used by SoC +framework to retrieve the information represented inside the OPP layer. + +opp_get_voltage - Retrieve the voltage represented by the opp pointer. + Example: At a cpufreq transition to a different frequency, SoC + framework requires to set the voltage represented by the OPP using + the regulator framework to the Power Management chip providing the + voltage. + soc_switch_to_freq_voltage(freq) + { + /* do things */ + rcu_read_lock(); + opp = opp_find_freq_ceil(dev, &freq); + v = opp_get_voltage(opp); + rcu_read_unlock(); + if (v) + regulator_set_voltage(.., v); + /* do other things */ + } + +opp_get_freq - Retrieve the freq represented by the opp pointer. + Example: Lets say the SoC framework uses a couple of helper functions + we could pass opp pointers instead of doing additional parameters to + handle quiet a bit of data parameters. + soc_cpufreq_target(..) + { + /* do things.. */ + max_freq = ULONG_MAX; + rcu_read_lock(); + max_opp = opp_find_freq_floor(dev,&max_freq); + requested_opp = opp_find_freq_ceil(dev,&freq); + if (!IS_ERR(max_opp) && !IS_ERR(requested_opp)) + r = soc_test_validity(max_opp, requested_opp); + rcu_read_unlock(); + /* do other things */ + } + soc_test_validity(..) + { + if(opp_get_voltage(max_opp) < opp_get_voltage(requested_opp)) + return -EINVAL; + if(opp_get_freq(max_opp) < opp_get_freq(requested_opp)) + return -EINVAL; + /* do things.. */ + } + +opp_get_opp_count - Retrieve the number of available opps for a device + Example: Lets say a co-processor in the SoC needs to know the available + frequencies in a table, the main processor can notify as following: + soc_notify_coproc_available_frequencies() + { + /* Do things */ + rcu_read_lock(); + num_available = opp_get_opp_count(dev); + speeds = kzalloc(sizeof(u32) * num_available, GFP_KERNEL); + /* populate the table in increasing order */ + freq = 0; + while (!IS_ERR(opp = opp_find_freq_ceil(dev, &freq))) { + speeds[i] = freq; + freq++; + i++; + } + rcu_read_unlock(); + + soc_notify_coproc(AVAILABLE_FREQs, speeds, num_available); + /* Do other things */ + } + +6. Cpufreq Table Generation +=========================== +opp_init_cpufreq_table - cpufreq framework typically is initialized with + cpufreq_frequency_table_cpuinfo which is provided with the list of + frequencies that are available for operation. This function provides + a ready to use conversion routine to translate the OPP layer's internal + information about the available frequencies into a format readily + providable to cpufreq. + + WARNING: Do not use this function in interrupt context. + + Example: + soc_pm_init() + { + /* Do things */ + r = opp_init_cpufreq_table(dev, &freq_table); + if (!r) + cpufreq_frequency_table_cpuinfo(policy, freq_table); + /* Do other things */ + } + + NOTE: This function is available only if CONFIG_CPU_FREQ is enabled in + addition to CONFIG_PM as power management feature is required to + dynamically scale voltage and frequency in a system. + +7. Data Structures +================== +Typically an SoC contains multiple voltage domains which are variable. Each +domain is represented by a device pointer. The relationship to OPP can be +represented as follows: +SoC + |- device 1 + | |- opp 1 (availability, freq, voltage) + | |- opp 2 .. + ... ... + | `- opp n .. + |- device 2 + ... + `- device m + +OPP library maintains a internal list that the SoC framework populates and +accessed by various functions as described above. However, the structures +representing the actual OPPs and domains are internal to the OPP library itself +to allow for suitable abstraction reusable across systems. + +struct opp - The internal data structure of OPP library which is used to + represent an OPP. In addition to the freq, voltage, availability + information, it also contains internal book keeping information required + for the OPP library to operate on. Pointer to this structure is + provided back to the users such as SoC framework to be used as a + identifier for OPP in the interactions with OPP layer. + + WARNING: The struct opp pointer should not be parsed or modified by the + users. The defaults of for an instance is populated by opp_add, but the + availability of the OPP can be modified by opp_enable/disable functions. + +struct device - This is used to identify a domain to the OPP layer. The + nature of the device and it's implementation is left to the user of + OPP library such as the SoC framework. + +Overall, in a simplistic view, the data structure operations is represented as +following: + +Initialization / modification: + +-----+ /- opp_enable +opp_add --> | opp | <------- + | +-----+ \- opp_disable + \-------> domain_info(device) + +Search functions: + /-- opp_find_freq_ceil ---\ +-----+ +domain_info<---- opp_find_freq_exact -----> | opp | + \-- opp_find_freq_floor ---/ +-----+ + +Retrieval functions: ++-----+ /- opp_get_voltage +| opp | <--- ++-----+ \- opp_get_freq + +domain_info <- opp_get_opp_count diff --git a/Documentation/power/runtime_pm.txt b/Documentation/power/runtime_pm.txt index 55b859b3bc72..489e9bacd165 100644 --- a/Documentation/power/runtime_pm.txt +++ b/Documentation/power/runtime_pm.txt @@ -1,6 +1,7 @@ Run-time Power Management Framework for I/O Devices (C) 2009 Rafael J. Wysocki <rjw@sisk.pl>, Novell Inc. +(C) 2010 Alan Stern <stern@rowland.harvard.edu> 1. Introduction @@ -157,7 +158,8 @@ rules: to execute it, the other callbacks will not be executed for the same device. * A request to execute ->runtime_resume() will cancel any pending or - scheduled requests to execute the other callbacks for the same device. + scheduled requests to execute the other callbacks for the same device, + except for scheduled autosuspends. 3. Run-time PM Device Fields @@ -165,7 +167,7 @@ The following device run-time PM fields are present in 'struct dev_pm_info', as defined in include/linux/pm.h: struct timer_list suspend_timer; - - timer used for scheduling (delayed) suspend request + - timer used for scheduling (delayed) suspend and autosuspend requests unsigned long timer_expires; - timer expiration time, in jiffies (if this is different from zero, the @@ -230,6 +232,28 @@ defined in include/linux/pm.h: interface; it may only be modified with the help of the pm_runtime_allow() and pm_runtime_forbid() helper functions + unsigned int no_callbacks; + - indicates that the device does not use the run-time PM callbacks (see + Section 8); it may be modified only by the pm_runtime_no_callbacks() + helper function + + unsigned int use_autosuspend; + - indicates that the device's driver supports delayed autosuspend (see + Section 9); it may be modified only by the + pm_runtime{_dont}_use_autosuspend() helper functions + + unsigned int timer_autosuspends; + - indicates that the PM core should attempt to carry out an autosuspend + when the timer expires rather than a normal suspend + + int autosuspend_delay; + - the delay time (in milliseconds) to be used for autosuspend + + unsigned long last_busy; + - the time (in jiffies) when the pm_runtime_mark_last_busy() helper + function was last called for this device; used in calculating inactivity + periods for autosuspend + All of the above fields are members of the 'power' member of 'struct device'. 4. Run-time PM Device Helper Functions @@ -255,6 +279,12 @@ drivers/base/power/runtime.c and include/linux/pm_runtime.h: error code on failure, where -EAGAIN or -EBUSY means it is safe to attempt to suspend the device again in future + int pm_runtime_autosuspend(struct device *dev); + - same as pm_runtime_suspend() except that the autosuspend delay is taken + into account; if pm_runtime_autosuspend_expiration() says the delay has + not yet expired then an autosuspend is scheduled for the appropriate time + and 0 is returned + int pm_runtime_resume(struct device *dev); - execute the subsystem-level resume callback for the device; returns 0 on success, 1 if the device's run-time PM status was already 'active' or @@ -267,6 +297,11 @@ drivers/base/power/runtime.c and include/linux/pm_runtime.h: device (the request is represented by a work item in pm_wq); returns 0 on success or error code if the request has not been queued up + int pm_request_autosuspend(struct device *dev); + - schedule the execution of the subsystem-level suspend callback for the + device when the autosuspend delay has expired; if the delay has already + expired then the work item is queued up immediately + int pm_schedule_suspend(struct device *dev, unsigned int delay); - schedule the execution of the subsystem-level suspend callback for the device in future, where 'delay' is the time to wait before queuing up a @@ -298,12 +333,20 @@ drivers/base/power/runtime.c and include/linux/pm_runtime.h: - decrement the device's usage counter int pm_runtime_put(struct device *dev); - - decrement the device's usage counter, run pm_request_idle(dev) and return - its result + - decrement the device's usage counter; if the result is 0 then run + pm_request_idle(dev) and return its result + + int pm_runtime_put_autosuspend(struct device *dev); + - decrement the device's usage counter; if the result is 0 then run + pm_request_autosuspend(dev) and return its result int pm_runtime_put_sync(struct device *dev); - - decrement the device's usage counter, run pm_runtime_idle(dev) and return - its result + - decrement the device's usage counter; if the result is 0 then run + pm_runtime_idle(dev) and return its result + + int pm_runtime_put_sync_autosuspend(struct device *dev); + - decrement the device's usage counter; if the result is 0 then run + pm_runtime_autosuspend(dev) and return its result void pm_runtime_enable(struct device *dev); - enable the run-time PM helper functions to run the device bus type's @@ -349,19 +392,51 @@ drivers/base/power/runtime.c and include/linux/pm_runtime.h: counter (used by the /sys/devices/.../power/control interface to effectively prevent the device from being power managed at run time) + void pm_runtime_no_callbacks(struct device *dev); + - set the power.no_callbacks flag for the device and remove the run-time + PM attributes from /sys/devices/.../power (or prevent them from being + added when the device is registered) + + void pm_runtime_mark_last_busy(struct device *dev); + - set the power.last_busy field to the current time + + void pm_runtime_use_autosuspend(struct device *dev); + - set the power.use_autosuspend flag, enabling autosuspend delays + + void pm_runtime_dont_use_autosuspend(struct device *dev); + - clear the power.use_autosuspend flag, disabling autosuspend delays + + void pm_runtime_set_autosuspend_delay(struct device *dev, int delay); + - set the power.autosuspend_delay value to 'delay' (expressed in + milliseconds); if 'delay' is negative then run-time suspends are + prevented + + unsigned long pm_runtime_autosuspend_expiration(struct device *dev); + - calculate the time when the current autosuspend delay period will expire, + based on power.last_busy and power.autosuspend_delay; if the delay time + is 1000 ms or larger then the expiration time is rounded up to the + nearest second; returns 0 if the delay period has already expired or + power.use_autosuspend isn't set, otherwise returns the expiration time + in jiffies + It is safe to execute the following helper functions from interrupt context: pm_request_idle() +pm_request_autosuspend() pm_schedule_suspend() pm_request_resume() pm_runtime_get_noresume() pm_runtime_get() pm_runtime_put_noidle() pm_runtime_put() +pm_runtime_put_autosuspend() +pm_runtime_enable() pm_suspend_ignore_children() pm_runtime_set_active() pm_runtime_set_suspended() -pm_runtime_enable() +pm_runtime_suspended() +pm_runtime_mark_last_busy() +pm_runtime_autosuspend_expiration() 5. Run-time PM Initialization, Device Probing and Removal @@ -524,3 +599,141 @@ poweroff and run-time suspend callback, and similarly for system resume, thaw, restore, and run-time resume, can achieve this with the help of the UNIVERSAL_DEV_PM_OPS macro defined in include/linux/pm.h (possibly setting its last argument to NULL). + +8. "No-Callback" Devices + +Some "devices" are only logical sub-devices of their parent and cannot be +power-managed on their own. (The prototype example is a USB interface. Entire +USB devices can go into low-power mode or send wake-up requests, but neither is +possible for individual interfaces.) The drivers for these devices have no +need of run-time PM callbacks; if the callbacks did exist, ->runtime_suspend() +and ->runtime_resume() would always return 0 without doing anything else and +->runtime_idle() would always call pm_runtime_suspend(). + +Subsystems can tell the PM core about these devices by calling +pm_runtime_no_callbacks(). This should be done after the device structure is +initialized and before it is registered (although after device registration is +also okay). The routine will set the device's power.no_callbacks flag and +prevent the non-debugging run-time PM sysfs attributes from being created. + +When power.no_callbacks is set, the PM core will not invoke the +->runtime_idle(), ->runtime_suspend(), or ->runtime_resume() callbacks. +Instead it will assume that suspends and resumes always succeed and that idle +devices should be suspended. + +As a consequence, the PM core will never directly inform the device's subsystem +or driver about run-time power changes. Instead, the driver for the device's +parent must take responsibility for telling the device's driver when the +parent's power state changes. + +9. Autosuspend, or automatically-delayed suspends + +Changing a device's power state isn't free; it requires both time and energy. +A device should be put in a low-power state only when there's some reason to +think it will remain in that state for a substantial time. A common heuristic +says that a device which hasn't been used for a while is liable to remain +unused; following this advice, drivers should not allow devices to be suspended +at run-time until they have been inactive for some minimum period. Even when +the heuristic ends up being non-optimal, it will still prevent devices from +"bouncing" too rapidly between low-power and full-power states. + +The term "autosuspend" is an historical remnant. It doesn't mean that the +device is automatically suspended (the subsystem or driver still has to call +the appropriate PM routines); rather it means that run-time suspends will +automatically be delayed until the desired period of inactivity has elapsed. + +Inactivity is determined based on the power.last_busy field. Drivers should +call pm_runtime_mark_last_busy() to update this field after carrying out I/O, +typically just before calling pm_runtime_put_autosuspend(). The desired length +of the inactivity period is a matter of policy. Subsystems can set this length +initially by calling pm_runtime_set_autosuspend_delay(), but after device +registration the length should be controlled by user space, using the +/sys/devices/.../power/autosuspend_delay_ms attribute. + +In order to use autosuspend, subsystems or drivers must call +pm_runtime_use_autosuspend() (preferably before registering the device), and +thereafter they should use the various *_autosuspend() helper functions instead +of the non-autosuspend counterparts: + + Instead of: pm_runtime_suspend use: pm_runtime_autosuspend; + Instead of: pm_schedule_suspend use: pm_request_autosuspend; + Instead of: pm_runtime_put use: pm_runtime_put_autosuspend; + Instead of: pm_runtime_put_sync use: pm_runtime_put_sync_autosuspend. + +Drivers may also continue to use the non-autosuspend helper functions; they +will behave normally, not taking the autosuspend delay into account. +Similarly, if the power.use_autosuspend field isn't set then the autosuspend +helper functions will behave just like the non-autosuspend counterparts. + +The implementation is well suited for asynchronous use in interrupt contexts. +However such use inevitably involves races, because the PM core can't +synchronize ->runtime_suspend() callbacks with the arrival of I/O requests. +This synchronization must be handled by the driver, using its private lock. +Here is a schematic pseudo-code example: + + foo_read_or_write(struct foo_priv *foo, void *data) + { + lock(&foo->private_lock); + add_request_to_io_queue(foo, data); + if (foo->num_pending_requests++ == 0) + pm_runtime_get(&foo->dev); + if (!foo->is_suspended) + foo_process_next_request(foo); + unlock(&foo->private_lock); + } + + foo_io_completion(struct foo_priv *foo, void *req) + { + lock(&foo->private_lock); + if (--foo->num_pending_requests == 0) { + pm_runtime_mark_last_busy(&foo->dev); + pm_runtime_put_autosuspend(&foo->dev); + } else { + foo_process_next_request(foo); + } + unlock(&foo->private_lock); + /* Send req result back to the user ... */ + } + + int foo_runtime_suspend(struct device *dev) + { + struct foo_priv foo = container_of(dev, ...); + int ret = 0; + + lock(&foo->private_lock); + if (foo->num_pending_requests > 0) { + ret = -EBUSY; + } else { + /* ... suspend the device ... */ + foo->is_suspended = 1; + } + unlock(&foo->private_lock); + return ret; + } + + int foo_runtime_resume(struct device *dev) + { + struct foo_priv foo = container_of(dev, ...); + + lock(&foo->private_lock); + /* ... resume the device ... */ + foo->is_suspended = 0; + pm_runtime_mark_last_busy(&foo->dev); + if (foo->num_pending_requests > 0) + foo_process_requests(foo); + unlock(&foo->private_lock); + return 0; + } + +The important point is that after foo_io_completion() asks for an autosuspend, +the foo_runtime_suspend() callback may race with foo_read_or_write(). +Therefore foo_runtime_suspend() has to check whether there are any pending I/O +requests (while holding the private lock) before allowing the suspend to +proceed. + +In addition, the power.autosuspend_delay field can be changed by user space at +any time. If a driver cares about this, it can call +pm_runtime_autosuspend_expiration() from within the ->runtime_suspend() +callback while holding its private lock. If the function returns a nonzero +value then the delay has not yet expired and the callback should return +-EAGAIN. diff --git a/Documentation/power/s2ram.txt b/Documentation/power/s2ram.txt index 514b94fc931e..1bdfa0443773 100644 --- a/Documentation/power/s2ram.txt +++ b/Documentation/power/s2ram.txt @@ -49,6 +49,13 @@ machine that doesn't boot) is: device (lspci and /sys/devices/pci* is your friend), and see if you can fix it, disable it, or trace into its resume function. + If no device matches the hash (or any matches appear to be false positives), + the culprit may be a device from a loadable kernel module that is not loaded + until after the hash is checked. You can check the hash against the current + devices again after more modules are loaded using sysfs: + + cat /sys/power/pm_trace_dev_match + For example, the above happens to be the VGA device on my EVO, which I used to run with "radeonfb" (it's an ATI Radeon mobility). It turns out that "radeonfb" simply cannot resume that device - it tries to set the diff --git a/Documentation/power/swsusp.txt b/Documentation/power/swsusp.txt index 9d60ab717a7b..ea718891a665 100644 --- a/Documentation/power/swsusp.txt +++ b/Documentation/power/swsusp.txt @@ -66,7 +66,8 @@ swsusp saves the state of the machine into active swaps and then reboots or powerdowns. You must explicitly specify the swap partition to resume from with ``resume='' kernel option. If signature is found it loads and restores saved state. If the option ``noresume'' is specified as a boot parameter, it skips -the resuming. +the resuming. If the option ``hibernate=nocompress'' is specified as a boot +parameter, it saves hibernation image without compression. In the meantime while the system is suspended you should not add/remove any of the hardware, write to the filesystems, etc. diff --git a/Documentation/powerpc/dts-bindings/fsl/spi.txt b/Documentation/powerpc/dts-bindings/fsl/spi.txt index 80510c018eea..777abd7399d5 100644 --- a/Documentation/powerpc/dts-bindings/fsl/spi.txt +++ b/Documentation/powerpc/dts-bindings/fsl/spi.txt @@ -1,7 +1,9 @@ * SPI (Serial Peripheral Interface) Required properties: -- cell-index : SPI controller index. +- cell-index : QE SPI subblock index. + 0: QE subblock SPI1 + 1: QE subblock SPI2 - compatible : should be "fsl,spi". - mode : the SPI operation mode, it can be "cpu" or "cpu-qe". - reg : Offset and length of the register set for the device @@ -29,3 +31,23 @@ Example: gpios = <&gpio 18 1 // device reg=<0> &gpio 19 1>; // device reg=<1> }; + + +* eSPI (Enhanced Serial Peripheral Interface) + +Required properties: +- compatible : should be "fsl,mpc8536-espi". +- reg : Offset and length of the register set for the device. +- interrupts : should contain eSPI interrupt, the device has one interrupt. +- fsl,espi-num-chipselects : the number of the chipselect signals. + +Example: + spi@110000 { + #address-cells = <1>; + #size-cells = <0>; + compatible = "fsl,mpc8536-espi"; + reg = <0x110000 0x1000>; + interrupts = <53 0x2>; + interrupt-parent = <&mpic>; + fsl,espi-num-chipselects = <4>; + }; diff --git a/Documentation/vm/page-types.c b/Documentation/vm/page-types.c index ccd951fa94ee..cc96ee2666f2 100644 --- a/Documentation/vm/page-types.c +++ b/Documentation/vm/page-types.c @@ -478,7 +478,7 @@ static void prepare_hwpoison_fd(void) } if (opt_unpoison && !hwpoison_forget_fd) { - sprintf(buf, "%s/renew-pfn", hwpoison_debug_fs); + sprintf(buf, "%s/unpoison-pfn", hwpoison_debug_fs); hwpoison_forget_fd = checked_open(buf, O_WRONLY); } } diff --git a/Documentation/x86/x86_64/kernel-stacks b/Documentation/x86/x86_64/kernel-stacks index 5ad65d51fb95..a01eec5d1d0b 100644 --- a/Documentation/x86/x86_64/kernel-stacks +++ b/Documentation/x86/x86_64/kernel-stacks @@ -18,9 +18,9 @@ specialized stacks contain no useful data. The main CPU stacks are: Used for external hardware interrupts. If this is the first external hardware interrupt (i.e. not a nested hardware interrupt) then the kernel switches from the current task to the interrupt stack. Like - the split thread and interrupt stacks on i386 (with CONFIG_4KSTACKS), - this gives more room for kernel interrupt processing without having - to increase the size of every per thread stack. + the split thread and interrupt stacks on i386, this gives more room + for kernel interrupt processing without having to increase the size + of every per thread stack. The interrupt stack is also used when processing a softirq. |