Q: How to reboot using kexec?

[Forza-tng]

Hi,

I note that openrc-shutdown supports --kexec option. Does it mean it is possible to load a kernel and initrd and then have openrc call kexec to boot the loaded kernel instead of doing a normal reboot? If so, how can I enable this option?

I tried calling openrc-shutdown manually, but that does not work. It says it will reboot, but nothing actually happens.

# openrc-shutdown -v --kexec now
Broadcast message from root@static (pts/0) (Sun Feb  2 18:16:31 2025):
The system will reboot now

Using Gentoo with openrc-0.55.1

For now I created a service kexec-boot that I added to the shutdown runlevel.

#!/sbin/openrc-run
description="Execute kexec if a kernel is preloaded, otherwise do a normal reboot"
depend() {
    after *
}
start_pre() {
    if yesno ${RC_REBOOT}; then
        if [ -f /sys/kernel/kexec_loaded ] && [ "$(cat /sys/kernel/kexec_loaded)" -eq 1 ]; then
                einfo "Executing kexec..."
            sleep 10
                kexec -e
                eerror "kexec failed, proceeding with normal reboot"
        fi
    fi
}
status() {
    if [ -f /sys/kernel/kexec_loaded ] && [ "$(cat /sys/kernel/kexec_loaded)" -eq 1 ]; then
        einfo "A kernel is loaded for kexec"
    else
        einfo "No kernel is loaded for kexec"
    fi
}