Re: [PATCH] x86/boot: Reorganize and clean up the BIOS area reservation code

From	Linus Torvalds <torvalds@linux-foundation.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH] x86/boot: Reorganize and clean up the BIOS area reservation code
Date	2016-07-23 03:20 +0200
Message-ID	<rXTLH-4TG-3@gated-at.bofh.it> (permalink)
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On Fri, Jul 22, 2016 at 10:00 PM, Matt Fleming <matt@codeblueprint.co.uk> wrote:
>
> I suppose we could rewrite the page table mapping for those precious
> <1MB regions to coerce the firmware into accessing different pages
> instead of the 1:1 addresses and copy the regions elsewhere. Maybe.
> That assumes we don't hit other firmware bugs though.

.. it also assumes that firmware honors our page tables. Which at a
minimum won't be true for things like SMM, which happens with paging
entirely disabled.

And that's exactly the kind of code that touches some of the memory in
the low 1M region - things like the legacy keyboard state bits in the
low 4kB etc, for crazy old DOS days, iirc.

                Linus

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[PATCH] x86/ebda: If the EBDA is in lowmem, reserve only 4k for the EBDA Andy Lutomirski <luto@kernel.org> - 2016-07-21 03:40 +0200
  [PATCH] x86/boot: Reorganize and clean up the BIOS area reservation  code Ingo Molnar <mingo@kernel.org> - 2016-07-21 10:20 +0200
    Re: [PATCH] x86/boot: Reorganize and clean up the BIOS area  reservation code Ingo Molnar <mingo@kernel.org> - 2016-07-21 10:40 +0200
    Re: [PATCH] x86/boot: Reorganize and clean up the BIOS area reservation code "H. Peter Anvin" <hpa@zytor.com> - 2016-07-21 10:40 +0200
      Re: [PATCH] x86/boot: Reorganize and clean up the BIOS area  reservation code Ingo Molnar <mingo@kernel.org> - 2016-07-21 11:20 +0200
      Re: [PATCH] x86/boot: Reorganize and clean up the BIOS area  reservation code Ingo Molnar <mingo@kernel.org> - 2016-07-21 11:20 +0200
        Re: [PATCH] x86/boot: Reorganize and clean up the BIOS area reservation code "H. Peter Anvin" <hpa@zytor.com> - 2016-07-21 14:40 +0200
    Re: [PATCH] x86/boot: Reorganize and clean up the BIOS area  reservation code Andy Lutomirski <luto@amacapital.net> - 2016-07-21 17:00 +0200
      Re: [PATCH] x86/boot: Reorganize and clean up the BIOS area  reservation code Ingo Molnar <mingo@kernel.org> - 2016-07-21 18:20 +0200
        Re: [PATCH] x86/boot: Reorganize and clean up the BIOS area  reservation code Andy Lutomirski <luto@amacapital.net> - 2016-07-21 23:10 +0200
          Re: [PATCH] x86/boot: Reorganize and clean up the BIOS area reservation code "H. Peter Anvin" <hpa@zytor.com> - 2016-07-21 23:30 +0200
            Re: [PATCH] x86/boot: Reorganize and clean up the BIOS area  reservation code Andy Lutomirski <luto@amacapital.net> - 2016-07-21 23:50 +0200
              Re: [PATCH] x86/boot: Reorganize and clean up the BIOS area  reservation code Andy Lutomirski <luto@amacapital.net> - 2016-07-22 00:50 +0200
                Re: [PATCH] x86/boot: Reorganize and clean up the BIOS area  reservation code Matt Fleming <matt@codeblueprint.co.uk> - 2016-07-22 15:10 +0200
                Re: [PATCH] x86/boot: Reorganize and clean up the BIOS area  reservation code Linus Torvalds <torvalds@linux-foundation.org> - 2016-07-23 03:20 +0200

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