crash-recovery.sh

# We are called from initramfs:/init ( /project/admin/initramfs/init )
#
# Execution environment:
#   kernel is the crashkernel
#   we are pid 1
#   original root is mounted at /
#   root might be mounted "ro" (if we have that in the kernel command line of the crash kernel)
#   /dev is mounted (prepopulated by devtmpfs)
#   we are executed by bash

# graphics console is not yet working, because the replaced kernel
# most probably used a framebuffer driver which reinitialized the graphics adapter
# so it no longer runs in a mode initialized by bios/grub.
# These bios-settings can not be restored easily, because this would require
# real mode(true?), which kexec doesn't go through.
#
# We can start the framebuffer driver and get a working console (fbcon) if
# we just load the right driver for the graphics adapter.
#
# However, nouveau currently requires to much memory (because of debugging data) and
# would just create a out of memory kernel panic.
#
#modprobe bochs_drm   # DRM Support for bochs dispi vga interface (qemu stdvga)
#modprobe nouveau     # nvidia : requires 512MB memory....
#
# We can't use /dev/kmsg (kernel ring buffer), because it only accepts a very limited
# number of messages per time slot....
#
#exec >/dev/kmsg 2>&1
#
# So for now just use our serial console /dev/ttyS1 which hopefully is connected to another system.
#
exec >/dev/ttyS1 2>&1

reboot() {
	test "$1" && echo "$S $1"
	echo "+++++++++++++++++++++++++++++++++++++ reboot in 10s"
	sleep 10
	/sbin/reboot -f
}

free_space() {
	local path="$1"
	echo $(( $(stat -f -c %a "$path") *  $(stat -f -c %S "$path") ))
}

set -x
echo "+++++++++++++++++++++++++++++++++++++ crash recovery"

mount -n -t proc     proc     /proc
mount -n -t sysfs    sysfs    /sys

test -e /proc/vmcore || reboot "no crashdump"
core_size=$(stat -c %s /proc/vmcore)

mount -o remount,rw / /

if test -x /etc/local/crash-recovery.sh; then
	. /etc/local/crash-recovery.sh
	reboot "/etc/local/crash-recovery.sh has finished"
fi

if mount -L CRASHDUMP /mnt; then
	test -e /mnt/crash.vmcore && rm /mnt/crash.vmcore
	if (( $(free_space /mnt) - $core_size > 1024*1024*1024 )); then
		echo "+++++++++++++++++++++++++++++++++++++ saving crash dump to CRASHDUMP volume"
		cp /proc/vmcore /mnt/crash.vmcore
		umount /mnt
	else
		echo "+++++++++++++++++++++++++++++++++++++ not enough free space on CRASHDUMP volume"
	fi
	reboot
fi;

test -e /var/crash.vmcore && rm /var/crash.vmcore
if (( $(free_space /var) - $core_size > 1024*1024*1024 )); then
	echo "+++++++++++++++++++++++++++++++++++++ saving crash dump to /var"
	cp /proc/vmcore /var/crash.vmcore
else
	echo "+++++++++++++++++++++++++++++++++++++ not enough free space in /var"
fi
reboot