[RFC PATCH] efi_loader: conditionally enable SetvariableRT

[Ilias Apalodimas]

Hi Mark,

[...]

> >
> > Open questions:
> > Looking at the EFI spec, I can't find a documented way of notifying the OS
> > that the storage is volatile. I would like to send a hint to the OS about
> > that and I was thinking of adding a configuration table with the filename,
> > which U-Boot expects to be on the ESP. Alternatively we could add a device
> > path which would be a bit harder to parse from the userspace application,
> > but safer in case multiple ESPs are present.
>
> Should there be a way for the OS to opt-in to this new behaviour?

The feature itself is in a Kconfig option. If we agree on a way to
notify the OS that the variable storage is in RAM and hence volatile,
the OS is free to ignore it I guess

>
> > Since I am not too familiar with how BSDs treat and expose config tables,
> > we could instead add a RO efi variable with identical semantics, which
> > would be easier to read from userspace.
>
> There is an EFIIOC_GET_TABLE ioctl that allows retreiving a table by GUID.

Ah thanks. I am leaning towards an EFI variable now to signal the OS

[...]

/Ilias