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-rw-r--r--Documentation/admin-guide/kernel-parameters.txt87
1 files changed, 68 insertions, 19 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 46b826fcb5ad..d3814789304f 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -860,6 +860,10 @@
disable_radix [PPC]
Disable RADIX MMU mode on POWER9
+ disable_tlbie [PPC]
+ Disable TLBIE instruction. Currently does not work
+ with KVM, with HASH MMU, or with coherent accelerators.
+
disable_cpu_apicid= [X86,APIC,SMP]
Format: <int>
The number of initial APIC ID for the
@@ -1044,6 +1048,10 @@
specified address. The serial port must already be
setup and configured. Options are not yet supported.
+ sbi
+ Use RISC-V SBI (Supervisor Binary Interface) for early
+ console.
+
smh Use ARM semihosting calls for early console.
s3c2410,<addr>
@@ -1090,6 +1098,12 @@
the framebuffer, pass the 'ram' option so that it is
mapped with the correct attributes.
+ linflex,<addr>
+ Use early console provided by Freescale LinFlex UART
+ serial driver for NXP S32V234 SoCs. A valid base
+ address must be provided, and the serial port must
+ already be setup and configured.
+
earlyprintk= [X86,SH,ARM,M68k,S390]
earlyprintk=vga
earlyprintk=sclp
@@ -1197,12 +1211,6 @@
See comment before function elanfreq_setup() in
arch/x86/kernel/cpu/cpufreq/elanfreq.c.
- elevator= [IOSCHED]
- Format: { "mq-deadline" | "kyber" | "bfq" }
- See Documentation/block/deadline-iosched.rst,
- Documentation/block/kyber-iosched.rst and
- Documentation/block/bfq-iosched.rst for details.
-
elfcorehdr=[size[KMG]@]offset[KMG] [IA64,PPC,SH,X86,S390]
Specifies physical address of start of kernel core
image elf header and optionally the size. Generally
@@ -1732,6 +1740,11 @@
Note that using this option lowers the security
provided by tboot because it makes the system
vulnerable to DMA attacks.
+ nobounce [Default off]
+ Disable bounce buffer for unstrusted devices such as
+ the Thunderbolt devices. This will treat the untrusted
+ devices as the trusted ones, hence might expose security
+ risks of DMA attacks.
intel_idle.max_cstate= [KNL,HW,ACPI,X86]
0 disables intel_idle and fall back on acpi_idle.
@@ -1811,7 +1824,7 @@
synchronously.
iommu.passthrough=
- [ARM64] Configure DMA to bypass the IOMMU by default.
+ [ARM64, X86] Configure DMA to bypass the IOMMU by default.
Format: { "0" | "1" }
0 - Use IOMMU translation for DMA.
1 - Bypass the IOMMU for DMA.
@@ -2373,7 +2386,7 @@
machvec= [IA-64] Force the use of a particular machine-vector
(machvec) in a generic kernel.
- Example: machvec=hpzx1_swiotlb
+ Example: machvec=hpzx1
machtype= [Loongson] Share the same kernel image file between different
yeeloong laptop.
@@ -2545,7 +2558,7 @@
mem_encrypt=on: Activate SME
mem_encrypt=off: Do not activate SME
- Refer to Documentation/virtual/kvm/amd-memory-encryption.rst
+ Refer to Documentation/virt/kvm/amd-memory-encryption.rst
for details on when memory encryption can be activated.
mem_sleep_default= [SUSPEND] Default system suspend mode:
@@ -2604,7 +2617,7 @@
expose users to several CPU vulnerabilities.
Equivalent to: nopti [X86,PPC]
kpti=0 [ARM64]
- nospectre_v1 [PPC]
+ nospectre_v1 [X86,PPC]
nobp=0 [S390]
nospectre_v2 [X86,PPC,S390,ARM64]
spectre_v2_user=off [X86]
@@ -2965,9 +2978,9 @@
nosmt=force: Force disable SMT, cannot be undone
via the sysfs control file.
- nospectre_v1 [PPC] Disable mitigations for Spectre Variant 1 (bounds
- check bypass). With this option data leaks are possible
- in the system.
+ nospectre_v1 [X86,PPC] Disable mitigations for Spectre Variant 1
+ (bounds check bypass). With this option data leaks are
+ possible in the system.
nospectre_v2 [X86,PPC_FSL_BOOK3E,ARM64] Disable all mitigations for
the Spectre variant 2 (indirect branch prediction)
@@ -3837,12 +3850,13 @@
RCU_BOOST is not set, valid values are 0-99 and
the default is zero (non-realtime operation).
- rcutree.rcu_nocb_leader_stride= [KNL]
- Set the number of NOCB kthread groups, which
- defaults to the square root of the number of
- CPUs. Larger numbers reduces the wakeup overhead
- on the per-CPU grace-period kthreads, but increases
- that same overhead on each group's leader.
+ rcutree.rcu_nocb_gp_stride= [KNL]
+ Set the number of NOCB callback kthreads in
+ each group, which defaults to the square root
+ of the number of CPUs. Larger numbers reduce
+ the wakeup overhead on the global grace-period
+ kthread, but increases that same overhead on
+ each group's NOCB grace-period kthread.
rcutree.qhimark= [KNL]
Set threshold of queued RCU callbacks beyond which
@@ -4047,6 +4061,10 @@
rcutorture.verbose= [KNL]
Enable additional printk() statements.
+ rcupdate.rcu_cpu_stall_ftrace_dump= [KNL]
+ Dump ftrace buffer after reporting RCU CPU
+ stall warning.
+
rcupdate.rcu_cpu_stall_suppress= [KNL]
Suppress RCU CPU stall warning messages.
@@ -4090,6 +4108,13 @@
Run specified binary instead of /init from the ramdisk,
used for early userspace startup. See initrd.
+ rdrand= [X86]
+ force - Override the decision by the kernel to hide the
+ advertisement of RDRAND support (this affects
+ certain AMD processors because of buggy BIOS
+ support, specifically around the suspend/resume
+ path).
+
rdt= [HW,X86,RDT]
Turn on/off individual RDT features. List is:
cmt, mbmtotal, mbmlocal, l3cat, l3cdp, l2cat, l2cdp,
@@ -4620,6 +4645,11 @@
/sys/power/pm_test). Only available when CONFIG_PM_DEBUG
is set. Default value is 5.
+ svm= [PPC]
+ Format: { on | off | y | n | 1 | 0 }
+ This parameter controls use of the Protected
+ Execution Facility on pSeries.
+
swapaccount=[0|1]
[KNL] Enable accounting of swap in memory resource
controller if no parameter or 1 is given or disable
@@ -5305,3 +5335,22 @@
A hex value specifying bitmask with supplemental xhci
host controller quirks. Meaning of each bit can be
consulted in header drivers/usb/host/xhci.h.
+
+ xmon [PPC]
+ Format: { early | on | rw | ro | off }
+ Controls if xmon debugger is enabled. Default is off.
+ Passing only "xmon" is equivalent to "xmon=early".
+ early Call xmon as early as possible on boot; xmon
+ debugger is called from setup_arch().
+ on xmon debugger hooks will be installed so xmon
+ is only called on a kernel crash. Default mode,
+ i.e. either "ro" or "rw" mode, is controlled
+ with CONFIG_XMON_DEFAULT_RO_MODE.
+ rw xmon debugger hooks will be installed so xmon
+ is called only on a kernel crash, mode is write,
+ meaning SPR registers, memory and, other data
+ can be written using xmon commands.
+ ro same as "rw" option above but SPR registers,
+ memory, and other data can't be written using
+ xmon commands.
+ off xmon is disabled.