Debugging kernel panic on boot.

[Simon Andrews]

Since the release of the 2.6.22-x kernels one of our servers has failed 
to boot.  Something seems to be going wrong in the loading of the 
modules which allow it to mount the root partition and it dies very 
early on in the boot.  Going back to a 2.6.21 kernel makes everything 
work OK again.

I've reported this on bugzilla at:

https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=249853

..but would like to try to track down where it's going wrong.

The machine itself is slightly odd in that it has a SCSCI controller on 
it with no devices attached, and the system disk is IDE and is the only 
one connected.


There are a few odd messages during boot, but these appear both in the 
kernels which work and those which don't:

SCSI subsystem initialized
libata version 2.20 loaded.
ata_piix 0000:00:12.1: version 2.10ac1
ata1: PATA max UDMA/33 cmd 0x000101f0 ctl 0x000103f6 bmdma 0x00011050 irq 14
ata2: PATA max UDMA/33 cmd 0x00010170 ctl 0x00010376 bmdma 0x00011058 irq 15
scsi0 : ata_piix
ata1: port is slow to respond, please be patient (Status 0x80)
ATA: abnormal status 0x3F on port 0x000101f7
ata1.00: ata_hpa_resize 1: sectors = 488397168, hpa_sectors = 488397168
ata1.00: ATA-6: WDC WD2500BB-00KEA0, 08.05J08, max UDMA/100
ata1.00: 488397168 sectors, multi 16: LBA48
ata1.00: ata_hpa_resize 1: sectors = 488397168, hpa_sectors = 488397168
ata1.00: configured for UDMA/33
scsi1 : ata_piix

The failed boots finish with:

Trying to resume from /dev/sda3
Unable to access resume device (/dev/sda3)
Creating root device
Mounting root filesystem
mount: could not find filesystem '/dev/root'
Setting up other filesystems
Setting up new root fs
setuproot: moving /dev failed: No such file or directory
no fstab.sys, mounting internal defaults
setuproot: error mounting /proc: No such file or directory
setuproot: error mounting /sys: No such file or directory
unmounting old /dev
unmounting old /proc
unmounting old /sys
switchroot: mount failed: No such file or directory
Booting has failed
Kernel panic not syncing: Attempted to kill init!


..but these messages are apparently common to any failure to find the 
root partition.

Any suggestions as to what I can do to try to figure out exactly what is 
causing this failure?

Cheers

Simon.