Re: mounting route device with kernel 2.6/reiserfs

[Haines Brown]

Sorry to follow up on my own question, but further information has
come to light that may be of use. 

During the boot just before the kernel panic that says that VFS is
unable to mount the root fs, I get:

  kmod: failed to exec /sbin/modprob -s -k block-major-8 errno=2

I didn't think anything of this because I have not yet run depmod to
build the database for modprob. But I decided to do so (from chroot):

  :/# depmod -a
  depmod: Can't open /lib/modules/2.4.18-bf2.4/modules.dep for writing 

Well, this kernel is the one being used on the drive from which I
built the grub diskette, not the 2.6.7-1-386 that runs on the disk I'm
trying to boot from floppy. 

I find that I do have /lib/modules/2.6.7-1-386 on the target disk, and
when I do: 

  :/# ls -l modules 
  drwxr-xr-x 5 root root ...

If depmod is looking for the wrong thing, I wonder if the grub
diskette likewise misguided.

Haines Brown

=====

> I'm experiencing insconsistent results from the same grub
> configuration stanza when grub is installed on a hard disk MBR and
> when installed on a floppy. 
> 
> Specifically, I am able to boot a hard disk (sdc, on which grub is not
> yet installed) from from grub installed in the MBR of another disk,
> sda) by using the configuration stanza:
> 
>     kernel /vmlinuz ro root=/dev/sdc1
>     root (hd2,0)
> 
> When I put the same stanza on a grub floppy, I first experienced Error
> 15: File not found until I reversed the order:
> 
>     root (hd2,0)
>     kernel /vmlinuz root=/dev/sdc1 ro
> 
> For a reason I don't understand, this allowed me to begin the boot
> of the sdc disk from floppy up to the point of a kernal panic: 
> 
>     VFS: Cannot open root device "sdc1" or 08:21
>     Please append correct "root=" option
>     Kernel panic: VFS: Unable to mount root fs on 08:21
> 
> So it appears that booting from sda bootloader allows the root fs to
> be mounted, but not when I try to boot from the bootloader on
> diskette. 
> 
> I'm running kernel 2.6.7-1-386 on sdc (and kernel 2.4.18-bf2.4 on
> sda). I gather that when people compile the kernel they sometimes
> cannot load the root fs, but the kernel I'm using is a stock kernel
> that I did not recompile. 
> 
> I'm also worried that perhaps the filesystem I'm using somehow
> prevents mounting the root. Both sda and sdc are using reiserfs. The
> boot floppy, I believe, is vfat. 
> 
> I cannot see from the above information that the location of root can
> be the problem. The root partition is sdc1, and there's a symlink 
> /vmlinuz -> /boot/vmlinuz-2.6.7-1-386. I'm running sarge/testing on
> both sda and sdc. There's no /boot/grub directory on sdc because I've
> not installed grub on it yet.