Re: Grub get and set efi variables

[SevenBits <sevenbitstech@gmail.com>]

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On Wednesday, November 4, 2015, Andrei Borzenkov <arvidjaar@gmail.com>
wrote:

> 04.11.2015 02:05, Mat Troi пишет:
>
>> Hi SevenBits,
>>
>> Thanks for letting me know.  Out of curiosity, any particular reason why
>> this patch did not get merged?  It looks to be a useful feature.
>>
>>
> First, this patch was reverse patch :)


Yeah, I think I had accidentally passed the arguments to the diff command
in the wrong order.


>
> I am not convinced making it easy to set EFI variable from within GRUB is
> good thing, because there are known reports about systems rendered
> unbootable by writing too much into EFI flash. What is your use case that
> absolutely requires setting EFI variables? How are you going to implement
> it on other platforms?


I should probably note that I wrote this patch for a specific project of
mine which required the ability to read UEFI variables. I added in write
functionality for good measure because I could. But I agree, this would
only encourage tinkering and users messing with their systems and
potentially bricking it, which would of course be blamed on GRUB.


>
> Reading does not harm and may be useful, but then it should provide
> generic interface to access arbitrary vendor namespace, not only EFI global
> variables, and handle arbitrary binary data, even if initial implementation
> handles only subset of them. Once someone starts to use it changing it will
> be much more difficult.
>
> Maybe it should take hints how to interpret variable values, or have
> format option akin to printf.


I would be happy to resume work on this, and debase it on the current code,
if GRUB has a clear need for such functionality. I would prefer to have it
be clear what the patch should consist of, though.

A key question would be how to e.g. handle arbitrary data stored in
variables if it is not something easily represent able like a string. Right
now, the patch stores it's value into an environment variable specified by
the user. Unless the powers that be think otherwise, I think this is the
best way to go.


>
> Thanks,
>> Mat
>>
>> On Tue, Nov 3, 2015 at 12:12 PM, SevenBits <sevenbitstech@gmail.com>
>> wrote:
>>
>> On Tuesday, November 3, 2015, Mat Troi <mattroisang@gmail.com> wrote:
>>>
>>> Hi,
>>>>
>>>> Searching through google, I see there was an email thread to add a patch
>>>> for getting and setting efi variable in GRUB2.
>>>> https://lists.gnu.org/archive/html/grub-devel/2013-11/msg00328.html
>>>>
>>>> However, looking at the tree, it doesn't look like this patch was added,
>>>> am I missing something?  Does anyone know if we have command to get/set
>>>> efi
>>>> variables in GRUB2?
>>>>
>>>>
>>>>
>>>> http://git.savannah.gnu.org/gitweb/?p=grub.git;a=tree;f=grub-core/commands/efi;h=005fd2efc9a2eede2a1eb1cab8081c360219107b;hb=HEAD
>>>>
>>>>
>>>> I'm the author of that patch. No, it was never merged into the tree. As
>>> far as I know, there is no equivalent functionality; GRUB does not
>>> support
>>> this feature.
>>>
>>>
>>> Thanks,
>>>> Mat
>>>>
>>>>
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>>>
>>>
>>
>>
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>
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