Re: Grub get and set efi variables

[SevenBits]

On Wednesday, November 4, 2015, Andrei Borzenkov <address@hidden> 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 <address@hidden> wrote:
> >
> > > On Tuesday, November 3, 2015, Mat Troi <address@hidden> 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
> > >
> > > _______________________________________________
> > > Grub-devel mailing list
> > > address@hidden
> > > https://lists.gnu.org/mailman/listinfo/grub-devel
> >
> >
> >
> > _______________________________________________
> > Grub-devel mailing list
> > address@hidden
> > https://lists.gnu.org/mailman/listinfo/grub-devel
>
>
> _______________________________________________
> Grub-devel mailing list
> address@hidden
> https://lists.gnu.org/mailman/listinfo/grub-devel