diff options
Diffstat (limited to 'tools/testing/selftests/rcutorture/doc/initrd.txt')
| -rw-r--r-- | tools/testing/selftests/rcutorture/doc/initrd.txt | 99 |
1 files changed, 12 insertions, 87 deletions
diff --git a/tools/testing/selftests/rcutorture/doc/initrd.txt b/tools/testing/selftests/rcutorture/doc/initrd.txt index 833f826d6ec2..933b4fd12327 100644 --- a/tools/testing/selftests/rcutorture/doc/initrd.txt +++ b/tools/testing/selftests/rcutorture/doc/initrd.txt @@ -1,9 +1,12 @@ -This document describes one way to create the initrd directory hierarchy -in order to allow an initrd to be built into your kernel. The trick -here is to steal the initrd file used on your Linux laptop, Ubuntu in -this case. There are probably much better ways of doing this. +The rcutorture scripting tools automatically create the needed initrd +directory using dracut. Failing that, this tool will create an initrd +containing a single statically linked binary named "init" that loops +over a very long sleep() call. In both cases, this creation is done +by tools/testing/selftests/rcutorture/bin/mkinitrd.sh. -That said, here are the commands: +However, if you are attempting to run rcutorture on a system that does +not have dracut installed, and if you don't like the notion of static +linking, you might wish to press an existing initrd into service: ------------------------------------------------------------------------ cd tools/testing/selftests/rcutorture @@ -11,22 +14,7 @@ zcat /initrd.img > /tmp/initrd.img.zcat mkdir initrd cd initrd cpio -id < /tmp/initrd.img.zcat ------------------------------------------------------------------------- - -Another way to create an initramfs image is using "dracut"[1], which is -available on many distros, however the initramfs dracut generates is a cpio -archive with another cpio archive in it, so an extra step is needed to create -the initrd directory hierarchy. - -Here are the commands to create a initrd directory for rcutorture using -dracut: - ------------------------------------------------------------------------- -dracut --no-hostonly --no-hostonly-cmdline --module "base bash shutdown" /tmp/initramfs.img -cd tools/testing/selftests/rcutorture -mkdir initrd -cd initrd -/usr/lib/dracut/skipcpio /tmp/initramfs.img | zcat | cpio -id < /tmp/initramfs.img +# Manually verify that initrd contains needed binaries and libraries. ------------------------------------------------------------------------ Interestingly enough, if you are running rcutorture, you don't really @@ -39,75 +27,12 @@ with 0755 mode. ------------------------------------------------------------------------ #!/bin/sh -[ -d /dev ] || mkdir -m 0755 /dev -[ -d /root ] || mkdir -m 0700 /root -[ -d /sys ] || mkdir /sys -[ -d /proc ] || mkdir /proc -[ -d /tmp ] || mkdir /tmp -mkdir -p /var/lock -mount -t sysfs -o nodev,noexec,nosuid sysfs /sys -mount -t proc -o nodev,noexec,nosuid proc /proc -# Some things don't work properly without /etc/mtab. -ln -sf /proc/mounts /etc/mtab - -# Note that this only becomes /dev on the real filesystem if udev's scripts -# are used; which they will be, but it's worth pointing out -if ! mount -t devtmpfs -o mode=0755 udev /dev; then - echo "W: devtmpfs not available, falling back to tmpfs for /dev" - mount -t tmpfs -o mode=0755 udev /dev - [ -e /dev/console ] || mknod --mode=600 /dev/console c 5 1 - [ -e /dev/kmsg ] || mknod --mode=644 /dev/kmsg c 1 11 - [ -e /dev/null ] || mknod --mode=666 /dev/null c 1 3 -fi - -mkdir /dev/pts -mount -t devpts -o noexec,nosuid,gid=5,mode=0620 devpts /dev/pts || true -mount -t tmpfs -o "nosuid,size=20%,mode=0755" tmpfs /run -mkdir /run/initramfs -# compatibility symlink for the pre-oneiric locations -ln -s /run/initramfs /dev/.initramfs - -# Export relevant variables -export ROOT= -export ROOTDELAY= -export ROOTFLAGS= -export ROOTFSTYPE= -export IP= -export BOOT= -export BOOTIF= -export UBIMTD= -export break= -export init=/sbin/init -export quiet=n -export readonly=y -export rootmnt=/root -export debug= -export panic= -export blacklist= -export resume= -export resume_offset= -export recovery= - -for i in /sys/devices/system/cpu/cpu*/online -do - case $i in - '/sys/devices/system/cpu/cpu0/online') - ;; - '/sys/devices/system/cpu/cpu*/online') - ;; - *) - echo 1 > $i - ;; - esac -done - while : do sleep 10 done ------------------------------------------------------------------------ -References: -[1]: https://dracut.wiki.kernel.org/index.php/Main_Page -[2]: http://blog.elastocloud.org/2015/06/rapid-linux-kernel-devtest-with-qemu.html -[3]: https://www.centos.org/forums/viewtopic.php?t=51621 +This approach also allows most of the binaries and libraries in the +initrd filesystem to be dispensed with, which can save significant +space in rcutorture's "res" directory. |