efi: Set Variable Runtime implementation

[Ilias Apalodimas]

Hi Shantur

On Fri, 24 Nov 2023 at 18:51, Shantur Rathore <i at shantur.com> wrote:
>
> Hi Heinrich,
>
> I am trying to work out how to enable the SetVariableRT service in
> U-Boot and came across your patch [1] which initially had the
> SetVariable RT service enabled in EFI but in the final patch this was
> removed.
> I am hoping to implement it on top of the SPI Flash EFI store [2] to
> be able to set Boot order and boot items from Linux the UEFI way.
>
> Can I pick your brain on why it was dropped in the patch?
> Is there any limitation in SetVariableRT service ?

I recently had a talk about it in Plumbers [0]. Generally speaking, RT
+ hardware owned by the kernel is a very weird combination since you
can't guarantee exclusive access to the flash or the bus and you have
to preserve a *lot* of code alive in u-boot.

I'll respond to your v1 patchset and we can discuss details there as well.

[0] https://lpc.events/event/17/contributions/1653/

Cheers
/Ilias
>
> Kind regards,
> Shantur
>
> [1] : https://patches.linaro.org/project/u-boot/patch/20200331060541.4212-1-xypron.glpk@gmx.de/
> [2] : https://patchwork.ozlabs.org/project/uboot/list/?series=383699