any updates? I seem to be stuck in a similar situation, except perhaps that my knowledge is very limited when it comes to xen and kernels...

I'm running Debian 5 lenny on linode and things are working great, but I just did an apt-get update, apt-get upgrade, and all of a sudden it seemed to have upgraded my kernel to 2.6.26-1-686 and gave me a message about initrd

"You are attempting to install an initrd kernel image... this will not work unless the boot loader is configured to use an initrd..."

I OK'd it (not being too sure what to do otherwise)

apt-get upgrade ended with some note about initrd:

"update-initramfs: Generating /boot/initrd.img-2.6.26-1-686"

Now I'm scared to try to boot my machine. Will I get a kernel panic?? Will it upgrade and keep working?? The machine is running fine now, but I'm guessing nothing will happen until a reboot.

This is a production host, and I'd be in a bit of mess if it goes down for too long. I emailed support, but haven't heard back yet.

Any ideas / insights will be more than welcome. I'm happy to do some reading and learn more, but I honestly don't know where to even start.

@yoav:

Are you running pv-grub or a Linode kernel? If it's the latter, the host completely ignores any kernels installed on your node, so it doesn't matter what Debian did.

I was reading through the PV_Grub link and got lost at the beginning...

On my linode configuration profile, the kernel is listed as 'Latest 2.6 Series (2.6.18.8-linode16)' so I guess it means I'm not using pv-grub.

So if I boot my virtual host now it won't boot into something else or try to replace the kernel or some kernel-panic like mark described??

That is certainly a relief. No plans on rebooting soon, but I hope there will be no surprises when I do.

Thanks mnordhoff!!

I finally solved the problem of the kernel panic. My menu.lst file was not correct. Here is what I am using - YMMV depending on your setup:

# Manual entries from Linode Wiki
default 0
timeout 5

### BEGIN AUTOMAGIC KERNELS LIST
## lines between the AUTOMAGIC KERNELS LIST markers will be modified
## by the debian update-grub script except for the default options below

## DO NOT UNCOMMENT THEM, Just edit them to your needs

## ## Start Default Options ##
## default kernel options
## default kernel options for automagic boot options
## If you want special options for specific kernels use kopt_x_y_z
## where x.y.z is kernel version. Minor versions can be omitted.
## e.g. kopt=root=/dev/hda1 ro
##      kopt_2_6_8=root=/dev/hdc1 ro
##      kopt_2_6_8_2_686=root=/dev/hdc2 ro
# kopt=root=ca00 ro

## default grub root device
## e.g. groot=(hd0,0)
# groot=(hd0)

## should update-grub create alternative automagic boot options
## e.g. alternative=true
##      alternative=false
# alternative=true

## should update-grub lock alternative automagic boot options
## e.g. lockalternative=true
##      lockalternative=false
# lockalternative=false

## additional options to use with the default boot option, but not with the
## alternatives
## e.g. defoptions=vga=791 resume=/dev/hda5
# defoptions=

## should update-grub lock old automagic boot options
## e.g. lockold=false
##      lockold=true
# lockold=false

## Xen hypervisor options to use with the default Xen boot option
# xenhopt=

## Xen Linux kernel options to use with the default Xen boot option
# xenkopt=console=tty0

## altoption boot targets option
## multiple altoptions lines are allowed
## e.g. altoptions=(extra menu suffix) extra boot options
##      altoptions=(single-user) single
# altoptions=(single-user mode) single

## controls how many kernels should be put into the menu.lst
## only counts the first occurence of a kernel, not the
## alternative kernel options
## e.g. howmany=all
##      howmany=7
# howmany=all

## should update-grub create memtest86 boot option
## e.g. memtest86=true
##      memtest86=false
# memtest86=true

## should update-grub adjust the value of the default booted system
## can be true or false
# updatedefaultentry=false

## should update-grub add savedefault to the default options
## can be true or false
# savedefault=false

## ## End Default Options ##

title           Debian GNU/Linux, kernel 2.6.26-2-xen-686 (2.6.26-15)
root            (hd0)
kernel          /boot/vmlinuz-2.6.26-2-xen-686 root=ca00 ro 
initrd          /boot/initrd.img-2.6.26-2-xen-686

title           Debian GNU/Linux, kernel 2.6.26-2-xen-686 (single-user mode)
root            (hd0)
kernel          /boot/vmlinuz-2.6.26-2-xen-686 root=ca00 ro single
initrd          /boot/initrd.img-2.6.26-2-xen-686

### END DEBIAN AUTOMAGIC KERNELS LIST

Most of the lines were created by update-grub command. I had to remove the root=UUID=****** with root=ca00 in all places where it occured.

Thank-you everyone for your help!

Mark

Didn't I specifically state that UUIDs should be removed, and that "root=ca00" should be used instead, a while ago? People, READ!

saman007uk: Yes, I did read your posts, and followed them. If you had READ my posts, you would have noticed the following:

I tried both root=ca00 and root=/dev/ca00, as suggested by another poster, and still encountered a kernel panic.

I posted the contents of my menu.lst file, and there were no UUIDs in that file.

My menu.lst file was missing several settings that have to be there (I assume, since it now works) that were inserted by update-grub. If someone had seen that, my problem would have been solved many days ago.

The point of my last post was to recap what finally worked for future readers who may have the same issues as I did. When one runs update-grub, it generates UUIDs in the menu.lst file, so I wanted to make sure any future readers caught that and fixed it.

Thank you for your help.

Mark

No need to install grub on the debian system, our boot loader is pv-grub on the linode host. The only thing you need is a correct menu.lst

A typical menu.lst would be :

default 0
timeout 5

title Debian (xen kernel)
root (hd0)
kernel /boot/vmlinux-2.6.26-xxxx root=/dev/xvda ro
initrd /boot/initrd.img-xxxx

The only thing you had missing at first was the initrd part.

Glad you got it working. I love being able to use pv-grub in such a painless way. Linode really rocks

tin0x3cc, thanks for the clarification. I was wondering what lines in my menu.lst were really necessary, but I have not had the time to remove them one at a time to see where my configuration breaks.

An interesting point about grub. I started this journey of discovery with Linux kernels, grub, and menu.lst because I wanted to get updated kernels and kernel security patches using Debian apt. I see now that I still may not need grub, but if my assumptions are correct, it will make updating the system easier, since all I will have to do is apt-get install a new kernel and run update-grub to boot with the new kernel.

If I did not use grub, I would have to edit by hand menu.lst each time I installed a new kernel. If I want to boot to a previous kernel, I just log in using Lish, run boot 1, and then select the previous version from the grub menu.

Is there an easier way to accomplish what I want?

Thanks!

Mark