Bug#505137: grub-common: grub-probe returns fat for ext3 root fs

[Felix Zielcke]

Am Sonntag, den 09.11.2008, 19:11 +0000 schrieb Scott Ashcroft:
> Package: grub-common
> Version: 1.96+20080724-11
> Severity: important
> 
> 
> grub-probe misdetects the root fs of one of my PCs (works fine on all others).
> 
...
> 
> It looks like grub-probe runs the FAT checks before the EXT2 check and I just happen to hit a false positive.
> 
> Hopefully 512 bytes of the partition should be enough to debug this?
> 
> sa:/# hexdump -Cn 512 /dev/sda1
> 00000000  eb 4a 90 00 65 6c 6c 20  38 2e 30 00 02 04 01 00  |.J..ell 8.0.....|
> 00000010  02 00 02 00 00 f8 4f 00  3f 00 ff 00 3f 00 00 00  |......O.?...?...|
> 00000020  86 39 01 00 80 00 29 09  08 d6 07 44 65 6c 6c 55  |.9....)....DellU|
> 00000030  74 69 6c 69 74 79 00 41  54 31 36 20 20 20 00 00  |tility.AT16   ..|
                                                                      ^^^
Seems like you had a FAT filesystem there.
If I make a 1 MB file and format it with mkfs.vfat then I have exactly
at the same place FAT12
If I then format the file with mkfs.ext2 the first 512 byte get zero'ed.
So I wonder why you still have a FAT header in there.

Maybe we could check if bpb.fstype contains FAT12/FAT16/FAT32, then this
would solve the problem for you but I don't know if it would introduce
one for others.

-- 
Felix Zielcke