gentoo kexec nano howto

gentoo kexec nano howto

Add "lzma" USE flag if kernel is zipped with lzma:

USE="lzma" emerge -av kexec-tools

Edit /etc/conf.d/kexec

Modify KNAME & INITRD:

BOOTPART="/boot"
KNAME="kernel-genkernel-x86_64-3.0.0-rc6"
...
INITRD="/boot/initramfs-genkernel-x86_64-3.0.0-rc6"
...
# load kexec image during bootup
LOAD_DURING_SHUTDOWN="no"

Add kexec to default run level

rc-update add kexec default

After /etc/init.d/kexec restart, kexec should be configured properly. And seems ``reboot'' will use kexec to reboot after that.

kexec command line:

Load:
kexec -l --append="cmd line" --initrd="initrd"

Exec loaded:
kexec -e

One interesting option is load new kernel if panic:

 -p, --load-panic     Load the new kernel for use on panic.

It might be useful to add this option to /etc/conf.d/kexec, if we need reboot kernel (or to a fall-back kernel) after kernel panic.