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SubjectRe: [PATCH v5 04/10] x86, efi: Reserve UEFI 2.8 Specific Purpose Memory for dax
On Fri, 13 Sep 2019 at 18:39, Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote:
>
> On Fri, 13 Sep 2019 at 17:39, Dan Williams <dan.j.williams@intel.com> wrote:
> >
> > On Fri, Sep 13, 2019 at 9:29 AM Ard Biesheuvel
> > <ard.biesheuvel@linaro.org> wrote:
> > >
> > > On Fri, 13 Sep 2019 at 17:22, Dan Williams <dan.j.williams@intel.com> wrote:
> > > >
> > > > On Fri, Sep 13, 2019 at 6:00 AM Ard Biesheuvel
> > > > <ard.biesheuvel@linaro.org> wrote:
> ...
> > > > > > diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
> > > > > > index 363bb9d00fa5..6d54d5c74347 100644
> > > > > > --- a/drivers/firmware/efi/efi.c
> > > > > > +++ b/drivers/firmware/efi/efi.c
> > > > > > @@ -52,6 +52,9 @@ struct efi __read_mostly efi = {
> > > > > > .tpm_log = EFI_INVALID_TABLE_ADDR,
> > > > > > .tpm_final_log = EFI_INVALID_TABLE_ADDR,
> > > > > > .mem_reserve = EFI_INVALID_TABLE_ADDR,
> > > > > > +#ifdef CONFIG_EFI_SOFT_RESERVE
> > > > > > + .flags = 1UL << EFI_MEM_SOFT_RESERVE,
> > > > > > +#endif
> > > > > > };
> > > > > > EXPORT_SYMBOL(efi);
> > > > > >
> > > > >
> > > > > I'd prefer it if we could call this EFI_MEM_NO_SOFT_RESERVE instead,
> > > > > and invert the meaning of the bit.
> > > >
> > > > ...but that would mean repeat occurrences of
> > > > "!efi_enabled(EFI_MEM_NO_SOFT_RESERVE)", doesn't the double negative
> > > > seem less readable to you?
> > > >
> > >
> > > One the one hand, yes. On the other hand, it is the only flag whose
> > > default is 'enabled' which is also less than ideal.
> >
> > Ok, I can get on board with "default 0" being the non exception state
> > of the flags.
> >
>
> In fact, let's just add something like
>
> static inline bool efi_soft_reserve_enabled(void)
> {
> return IS_ENABLED(CONFIG_EFI_SOFT_RESERVE) &&
> !efi_enabled(EFI_MEM_NO_SOFT_RESERVE);
> }
>
> to linux/efi.h and use that in the code?

Or even better, add just the declaration to linux.efi,h

bool __pure efi_soft_reserve_enabled(void);

and put one implementation in efi-stub-helper.c:

bool __pure efi_soft_reserve_enabled(void)
{
return IS_ENABLED(CONFIG_EFI_SOFT_RESERVE) &&
!efi_nosoftreserve;
}

and the one above in drivers/firmware/efi/efi.c

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