linux-kernel - Re: [PATCH v1 RESEND 2/2] x86/efi: Clean up a minor mistake in code comment

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Date:   Fri, 24 Mar 2017 17:04:32 +0800
From:   Baoquan He <bhe@...hat.com>
To:     Ard Biesheuvel <ard.biesheuvel@...aro.org>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Matt Fleming <matt@...eblueprint.co.uk>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, Borislav Petkov <bp@...en8.de>,
        "x86@...nel.org" <x86@...nel.org>,
        "linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>
Subject: Re: [PATCH v1 RESEND 2/2] x86/efi: Clean up a minor mistake in code
 comment

On 03/24/17 at 08:57am, Ard Biesheuvel wrote:
> On 23 March 2017 at 03:27, Baoquan He <bhe@...hat.com> wrote:
> > EFI allocate runtime services regions from EFI_VA_START, -4G, down
> > to -64G, EFI_VA_END.
> 
> OK, so is the size of the region 60 GB or 64 GB? This suggests 60 GB,
> but the comment you update suggests 64 GB.

Ah, sorry, here it should be -68G. The reserved EFI region is [-68G,
-4G), amount is 64G.

Thanks, will repost with updated log.

> 
> > The mechanism was introduced in
> > commit d2f7cbe7b26a7 ("x86/efi: Runtime services virtual mapping").
> >
> > Clean it up to avoid confusion.
> >
> > Signed-off-by: Baoquan He <bhe@...hat.com>
> > Cc: Matt Fleming <matt@...eblueprint.co.uk>
> > Cc: Ard Biesheuvel <ard.biesheuvel@...aro.org>
> > Cc: Thomas Gleixner <tglx@...utronix.de>
> > Cc: Ingo Molnar <mingo@...hat.com>
> > Cc: "H. Peter Anvin" <hpa@...or.com>
> > Cc: Borislav Petkov <bp@...en8.de>
> > Cc: x86@...nel.org
> > Cc: linux-efi@...r.kernel.org
> > ---
> >  arch/x86/platform/efi/efi_64.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
> > index a4695da..6cbf9e0 100644
> > --- a/arch/x86/platform/efi/efi_64.c
> > +++ b/arch/x86/platform/efi/efi_64.c
> > @@ -47,7 +47,7 @@
> >  #include <asm/pgalloc.h>
> >
> >  /*
> > - * We allocate runtime services regions bottom-up, starting from -4G, i.e.
> > + * We allocate runtime services regions top-down, starting from -4G, i.e.
> >   * 0xffff_ffff_0000_0000 and limit EFI VA mapping space to 64G.
> >   */
> >  static u64 efi_va = EFI_VA_START;
> > --
> > 2.5.5
> >