Is it possible to reboot a Linux OS without rebooting the hardware?

Solution 1:

I use kexec-reboot on nearly all of my production systems.

It works incredibly well, allowing me to bypass the long POST time on HP ProLiant servers and reduce the boot cycle from 5 minutes to ~45 seconds.

See: https://github.com/error10/kexec-reboot

The only caveat is that it doesn't seem to work on RHEL/CentOS 6.x systems booting UEFI. But most sane OS/hardware combinations work.

Solution 2:

Yes, it is possible. kexec will allow a Linux kernel to be booted directly from Linux without going through the BIOS boot process.

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Solution 3:

Yes. You must use kexec-tools. To make the life easier, I use kexec-reboot.

$sudo apt-get install kexec-tools
$wget https://raw.githubusercontent.com/vadmium/kexec-reboot/master/kexec-reboot
$chmod +x kexec-reboot
$sudo mv kexec-reboot /usr/local/sbin/kexec-reboot
$sudo /usr/local/sbin/kexec-reboot