(no subject) [GRUB boot problems]

Paolo paolo at gabubbi.it
Wed Jan 14 21:54:33 UTC 2004


Phil Schaffner said:
> On Tue, 2004-01-13 at 10:53, Paolo wrote:
>> Phil Schaffner said:
[...]
> Looks like quite a lot went on in this thread while I was off doing what
> they pay me for :-) but still no resolution.
>
>>From "info grub":
> -------------------------------------------------------------------------
> Creating a GRUB boot floppy
> ===========================
>
>    To create a GRUB boot floppy, you need to take the files `stage1'
> and `stage2' from the image directory, and write them to the first and
> the second block of the floppy disk, respectively.
>
>    *Caution:* This procedure will destroy any data currently stored on
> the floppy.
>
>    On a UNIX-like operating system, that is done with the following
> commands:
>
>      # cd /usr/share/grub/i386-pc
>      # dd if=stage1 of=/dev/fd0 bs=512 count=1
>      1+0 records in
>      1+0 records out
>      # dd if=stage2 of=/dev/fd0 bs=512 seek=1
>      153+1 records in
>      153+1 records out
>      #

Ok, done.
And it works :)

>    The device file name may be different. Consult the manual for your
> OS.
> -------------------------------------------------------------------------
>
> I can also e-mail you directly with a compressed grub floppy image,
> and/or a script to create a grub floppy with menu support, if it would
> help.
>
> After booting from the grub floppy you should be able to run "find
> /grub/stage1" and see what disk/partition it is on.  If my guess is
> correct that you have a problem with mapping to a different device at
> boot time then the session might look like this:
>
> 	grub> find /grub/stage1		# what you type at prompt
> 	(hd1,1)				# what grub finds

$grub> find /grub/stage1
$(hd1,1)

> You would have expected (hd0,1) if everything mapped the same on the
> boot as the installer or running system.

Right,
but I've got (hd1,1)

> Can also try to find other known system files to verify what grub sees
> as the other partitions, for example:
>
> 	grub> find /etc/fstab
> 	(hd1,2)

$ grub> find /etc/fstab
$ (hd1,2)

> Then boot to the recovery mode as you mention above.  Look at the
> /mnt/sysimage/boot/grub/device.map file (not in chroot mode) created
> from Anaconda and see how well it matches what grub sees booting from
> the floppy.  You can also run grub at the recovery command line

the content of that file is the following:

# this device map was generated by anaconda
(fd0)     /dev/fd0
(hd0)     /dev/hda

> with/without the "--device-map=/mnt/sysimage/boot/grub/device.map"
> switch and try the "find" commands as above.  If everything is the same,
> then I'm clueless.  If they differ, send the results from the
> floppy-boot grub and the rescue grub for further advice.

Yes, it is different:

$grub> find /grub/stage1
$(hd0,1)

and

$ grub> find /etc/fstab
$ (hd0,2)

Now I'm almost stuck,
I see we found out the problem but I don't know how to fix it.

Phil ? :-)

-- 
                    Paolo C.





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