Re: GRUB booting from FAT32?

[Jochen Hoenicke]

On Thursday 11 March 2004 22:43, Greg Trounson wrote:
> Greetings,
> 
> I have a dual-boot Linux/WinXP system that needs to be able to reboot to
> either OS on demand.
> 
> I figured the best(tidiest) way to do this is to have each OS modify
> GRUBs menu.lst and set the default before rebooting.  This would mean
> putting menu.lst et. al. somewhere where both Windows and Linux can see
> them, either installing an EXT2/3 writing driver under windows, or
> putting menu.lst on a FAT partition.  After playing with some windows
> EXT2 drivers, I decided to go with making the /boot partition FAT.
> 
> My /boot resides on a 256MB EXT3 partition at the beginning of the disk
> (hda1).
> 
> I would much rather use FAT32 than FAT16, as I don't fancy having to
> truncate all my kernel names and system maps to 8.3 characters.

First, long filenames and FAT32/16 are orthogonal: you can have FAT16
and long filenames.  You can even have long filenames on a FAT12
floppy disk.  The main difference between FAT32/FAT16 is the maximum
number of clusters.  Windows XP can't even handle FAT32 with less than
65527 clusters (with 4KB cluster this are 256 MB).

> I copied all files from the /boot partition to a safe location,
> re-defined /boot as FAT32 (with fdisk and mkdosfs) and copied the files
> back.  I had to copy grub.conf to menu.lst, as it used to be symlinked.
> 
> Now when I reboot, I get an Error 17 ("cannot mount selected partition").

As Okuji asked, do you have the latest version?  The grub error
message aren't very expressive but this means that some entry in the
boot sector or the filesystem type in the partition table is wrong.

> If I redefine the partition as FAT16(again with fdisk and mkdosfs) and
> re-copy the files, I don't get Error 17, I get Error 15 ("file not
> found").  I think I know why the Error 15 occurrs, since the menu.lst is
> located in /grub relative to the partition, not /boot/grub.

If you reinstall grub, grub should figure out itself where menu.lst
resides.  Of course, you also have to change your menu.lst to point to
/vmlinuz instead of /boot/vmlinuz.

> This would suggest to me that GRUB can read FAT16 but not FAT32, which
> seems to go against what's stated in the GRUB manual.
> 
> Has anyone else had any luck getting GRUB to read FAT32?

Yes, I don't have any problems accessing my FAT32 partition.

  Jochen

-- 
Jochen Hoenicke, University of Oldenburg, 26111 Oldenburg, Germany
Email: address@hidden  Tel: +49 441 798 3124