[PATCH] efi_loader: optional persistence of variables

[Tom Saeger]

On Tue, Mar 22, 2022 at 10:41:40PM +0100, Heinrich Schuchardt wrote:
> On 3/22/22 22:21, Tom Saeger wrote:
> > Since be66b89da306 ("efi_loader: configuration of variables store")
> > the choice of EFI_VARIABLE_FILE_STORE or EFI_MM_COMM_TEE
> > is mutually-exclusive, however efi_var_to_file also allows
> > for "neither".  Set Kconfig choice optional.
> > 
> > Signed-off-by: Tom Saeger <tom.saeger at oracle.com>
> > ---
> >   lib/efi_loader/Kconfig | 1 +
> >   1 file changed, 1 insertion(+)
> > 
> > diff --git a/lib/efi_loader/Kconfig b/lib/efi_loader/Kconfig
> > index e5e35fe51f65..9add2a286ff4 100644
> > --- a/lib/efi_loader/Kconfig
> > +++ b/lib/efi_loader/Kconfig
> > @@ -44,6 +44,7 @@ config EFI_SETUP_EARLY
> > 
> >   choice
> >   	prompt "Store for non-volatile UEFI variables"
> > +	optional
> 
> Storing non-volatile variables is required by the UEFI specification.
> 
> How should a user understand that a boot option he just created vanishes
> upon reboot?
> 
> Please, explain your use case.

bootefi ${kernel_addr}

in this case linux kernel for an Armv8 platform.
This platform does not want or need any variables to persist.

bootefi eventually calls efi_var_from_file(), where *NOT* defining
CONFIG_EFI_VARIABLE_FILE_STORE would allow this use case to work,
otherwise it fails.  This was possible before
be66b89da306 ("efi_loader: configuration of variables store").

Thoughts?

--Tom

> 
> Best regards
> 
> Heinrich
> 
> >   	default EFI_VARIABLE_FILE_STORE
> >   	help
> >   	  Select where non-volatile UEFI variables shall be stored.
> > 
> > base-commit: 5f68470d69f853b1652ebe93525b60064717fe2e
>