Boot old kernel if new kernel fails

soc · 10-15-2004, 06:05 AM

Hi,

I was thinking of something today, no idea if this is possible, but i'd might as well give it a try

Take this scenario:

You build a new (Linux 2.6) kernel and add it to GRUB. You reboot the system through the console and wait until the kernel you just compiled boots up.

After about 5 minutes you find out that the kernel doesn't boot (must have forgotten something heh

).

You log in to your APC (Remote Power Switch) and reboot the box.

Is it then possible in some way to make GRUB boot the old kernel (on a remote box, so no screen and only a power switch)?

/bin/bash · 10-15-2004, 07:15 AM

I don't know about grub but with lilo you can use the -R command.

Code:

       -R command line
              This  option  sets the default command for the boot loader the next
              time it executes. The boot loader will then erase this  line:  this
              is  a  once-only  command.  It is typically used in reboot scripts,
              just before calling `shutdown -r'.  Used without any arguments,  it
              will cancel a lock-ed or fallback command line.

So what you do is you use the /sbin/lilo -R command to tell lilo to boot the new kernel. Then when it boots lilo will erase this command so you are back to your default kernel. You must have a n append panic=30 in lilo.conf for the new kernel image so it will reboot automatically in the event of a panic.

jainashish · 10-15-2004, 09:21 AM

for grub you can add a line :
fallback <index # of title> (Note: index starts from 0)

in /boot/grub/menu.lst file

for more details ....read info pages on grub and to configuration file section

soc · 10-17-2004, 04:50 PM

Quote:

Originally posted by /bin/bash
I don't know about grub but with lilo you can use the -R command.

Thanks, seems LILO is the only one capable of doing that, I guess i'll have to try LILO then, thanks