Ok so i have Slack 12 with the 2.6.21.5.

I need to patch to include kdb debugger these are the steps i have taken

1) patch -p1 < ../kdb-v4.4-2.6.21.5-common-3
2) patch -p2 < ../kdb-v4.4-2.6.21.5-ci386-3
2.5) make xconfig - Select Built in debugger & KDB Modules
3) Make dep
4) make clean
5) make bzimage
5.5) cp arch/i386/boot/bzImage /boot/linuxkdb
6) make modules
7) make modules_install
8) change lilo.conf to add
image=/boot/linuxkdb
label=kdblinux
read-only
root=/dev/hda1

Which is the same as default entry from the original instalation except the boot image is now linuxkdb rather than vmlinuz.

When i select the original kernel everything boots ok

when i select the kdb patched kernel i get the error

thats the standard error when you don't have the correct filesystem in the kernel supported.

for e.g if it is a ext3 then you need to make sure you have the ext3 support in the kernel. Try and include it (Y instead of N or M ) and see if it works (replace ext3 with your filesystem).

If your kernel does not support the file system of your / (root) directory, as seems to be your case, you may either recompile your kernel with embedded support for it, as suggested by duryodhan or make an initrd, to load the filesystem support as a module.
To do this follow the instructions in
/boot/README.initrd

try recompiling the kernel with your file system set as <yes> instead of <modules>. that worked for me.

see readme.mkinitrd in /boot and you will have a good boot.

One other problem could be an incorrect / entry in your fstab - I had problems after a recompile with my primary disk becoming sda instead of hda so that might be worth checking

I got a similar error and I worked it out by booting a live cd and mounting the volume and then:

Might have something to do with this https://bugs.launchpad.net/ubuntu/+s...22/+bug/151146

I hope the command help you out.