Re: GRUB can't read FAT file system

[Andrey Borzenkov]

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В Sun, 08 Dec 2013 13:46:38 -0500
SevenBits <address@hidden> пишет:

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> Hello,
> 
> I've been having a rather strange problem with GRUB, one that I have
> been encountering for a while. For some reason, GRUB cannot read
> partitioned FAT file systems on my, as well as others', USB drives.
> This occurs on all GRUB releases I have tried, including the
> development version through git.
> 
> I have a standalone GRUB for EFI image that I generated with the
> grub-mkimage tool as follows. Notice that I have included the FAT
> module as part as PART_FAT:
> 
> ../grub-mkimage -d . --format x86_64-efi --config
> '/home/username/Desktop/grub.cfg' -o ~/Desktop/boot.efi boot linux
> ext2 normal configfile lspci ls loadenv help echo fat exfat multiboot
> multiboot2 terminal sleep loopback normal fixvideo iso9660 loadbios
> 

You need to include partition support. For EFI this would be at least
part_gpt and part_msdos.

> When I boot into GRUB and go into the normal prompt, trying to list
> list devices works, as I'll type verbatim here:
> 
> grub> ls
> (hd0) (hd1) (cd0)
> 
> Typing the following should work, but doesn't.
> 
> grub> ls (hd0)/
> error: unknown filesystem.
> 
> I know that (hd0) is the identifier for my USB drive, because the
> access indicator light flashes while that operation is being performed.
> 
> Now, if I format the USB drive to have a FAT filesystem but no
> partitions, the operation works. For instance, this command:
> 
>  sudo mkfs.vfat -I /dev/sdX -n LINUX
> 

First you said "partitioned" and now you show whole device and not
partition. What is correct?

> produces a drive that functions as expected.
> 
> This has happened not just to me, but to others that are using my
> compiled GRUB image as well. So I don't know if this is an issue with
> GRUB or something that I'm doing wrong. I've made dumb mistakes
> before, so this is a possibility. Any ideas any one has would be
> appreciated.
> 
> - -- SevenBits
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