EFI disk IO

EFI disk IO

[Phillip Susi]

IIRC, EFI provides filesystem IO support, so I was wondering: does
grub-efi use the EFI file IO calls, or does it still use its built in
partition and fs parsing modules, and only rely on EFI for the low level
disk block IO?

It seems like you would want to build the grub fs modules as EFI drivers
to extent the entire EFI system if needed, and rely on EFI for file IO.

Re: EFI disk IO

[Vladimir 'φ-coder/phcoder' Serbinenko]

[-- Attachment #1: Type: text/plain, Size: 858 bytes --]

On 01/06/2011 05:11 PM, Phillip Susi wrote:
> IIRC, EFI provides filesystem IO support, so I was wondering: does
> grub-efi use the EFI file IO calls, or does it still use its built in
> partition and fs parsing modules, and only rely on EFI for the low level
> disk block IO?
>
>   
GRUB uses own drivers.
> It seems like you would want to build the grub fs modules as EFI drivers
> to extent the entire EFI system if needed, and rely on EFI for file IO.
>
>   
It's not a goal of GRUB to extend a firmware. It's here to abstract from
it and load the kernels. It's especially true for such poor-design
firmwares as EFI
> _______________________________________________
> Grub-devel mailing list
> Grub-devel@gnu.org
> http://lists.gnu.org/mailman/listinfo/grub-devel
>
>   


-- 
Regards
Vladimir 'φ-coder/phcoder' Serbinenko



[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 294 bytes --]

Re: EFI disk IO

[Colin Watson]

On Thu, Jan 06, 2011 at 11:11:15AM -0500, Phillip Susi wrote:
> IIRC, EFI provides filesystem IO support,

Only for filesystems EFI supports, which is typically a much smaller
range than GRUB.  You're basically only guaranteed to get FAT, and as
far as I can tell it's only designed for reading from EFI System
Partitions or the equivalent.

> so I was wondering: does grub-efi use the EFI file IO calls, or does
> it still use its built in partition and fs parsing modules, and only
> rely on EFI for the low level disk block IO?

GRUB uses its own partition and file handling.

> It seems like you would want to build the grub fs modules as EFI drivers
> to extent the entire EFI system if needed, and rely on EFI for file IO.

It doesn't seem worth it given the extremely limited scope of the EFI
File Protocol.  It would be substantial work for little benefit, and
GRUB's own drivers probably work better for reading from general
filesystems anyway.

-- 
Colin Watson                                       [cjwatson@ubuntu.com]