[PATCH 1/1] efi_loader: provide variable BootOptionSupport

[Ilias Apalodimas]

Hi Mark,

On Fri, 11 Oct 2024 at 20:53, Mark Kettenis <mark.kettenis at xs4all.nl> wrote:
>
> > From: Heinrich Schuchardt <heinrich.schuchardt at canonical.com>
> > Date: Fri, 11 Oct 2024 19:33:40 +0200
>
> Hi Heinrich,
>
> > The UEFI variable BootOptionSupport is required by the UEFI specification
> > [1]. It reports if specific types of boot options are honored.
> >
> > We don't support any of these extras. So we should set the value 0.
>
> It also says:
>
>   "If the global variable is not present, then an installer or
>    application must act as if a value of 0 was returned."
>
> So until we support any of those extras, we don't have to provide that
> variable.
>
> > [1] 3.1.4 Boot Manager Capabilities, UEFI Specification 2.10 Errata A,

It does, but is there a problem with being explicit? Are you concerned
about the size growth?

Thanks
/Ilias
> >
> > Cc: Vincent Stehlé <vincent.stehle at arm.com>
> > Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt at canonical.com>
> > ---
> >  lib/efi_loader/efi_setup.c | 23 +++++++++++++++++++++++
> >  1 file changed, 23 insertions(+)
> >
> > diff --git a/lib/efi_loader/efi_setup.c b/lib/efi_loader/efi_setup.c
> > index a610e032d2f..05d035f4eb5 100644
> > --- a/lib/efi_loader/efi_setup.c
> > +++ b/lib/efi_loader/efi_setup.c
> > @@ -179,6 +179,22 @@ static efi_status_t efi_init_os_indications(void)
> >                                   &os_indications_supported, false);
> >  }
> >
> > +/**
> > + * efi_init_boot_options_support() - indicate supported boot option types
> > + */
> > +static efi_status_t efi_init_boot_options_support(void)
> > +{
> > +     u32 boot_options_support = 0;
> > +
> > +     return efi_set_variable_int(u"BootOptionSupport",
> > +                                 &efi_global_variable_guid,
> > +                                 EFI_VARIABLE_BOOTSERVICE_ACCESS |
> > +                                 EFI_VARIABLE_RUNTIME_ACCESS |
> > +                                 EFI_VARIABLE_READ_ONLY,
> > +                                 sizeof(boot_options_support),
> > +                                 &boot_options_support, false);
> > +}
> > +
> >  /**
> >   * efi_init_early() - handle initialization at early stage
> >   *
> > @@ -261,6 +277,13 @@ efi_status_t efi_init_obj_list(void)
> >       if (ret != EFI_SUCCESS)
> >               goto out;
> >
> > +     /* Indicate supported boot option types */
> > +     if (IS_ENABLED(CONFIG_EFI_BOOTMGR)) {
> > +             ret = efi_init_boot_options_support();
> > +             if (ret != EFI_SUCCESS)
> > +                     goto out;
> > +     }
> > +
> >       /* Initialize system table */
> >       ret = efi_initialize_system_table();
> >       if (ret != EFI_SUCCESS)
> > --
> > 2.45.2
> >
> >