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Date:   Sun, 6 Jun 2021 19:05:29 -0400
From:   Sasha Levin <sashal@kernel.org>
To:     Borislav Petkov <bp@alien8.de>
Cc:     Linus Torvalds <torvalds@linux-foundation.org>,
        Mike Rapoport <rppt@linux.ibm.com>, x86-ml <x86@kernel.org>,
        lkml <linux-kernel@vger.kernel.org>, James.Morris@microsoft.com
Subject: Re: [GIT PULL] x86/urgent for v5.13-rc5
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On Mon, Jun 07, 2021 at 12:07:58AM +0200, Borislav Petkov wrote:
>On Sun, Jun 06, 2021 at 02:23:21PM -0700, Linus Torvalds wrote:
>> On Sun, Jun 6, 2021 at 1:58 PM Mike Rapoport <rppt@linux.ibm.com> wrote:
>> >
>> > A while ago hpa said:
>> >
>> >         As far as I know, Windows 7 actually reserves all memory below
>> >         1 MiB to avoid BIOS bugs.
>> >
>> > (https://bugzilla.kernel.org/show_bug.cgi?id=16661#c2)
>>
>> It would be good to have that checked somehow.
>>
>> I don't think this matters on any machine with gigs of RAM, but I do
>> wonder about the people who want to do small configurations. Maybe
>> they've given up on x86?
>>
>> It also eats into that somewhat precious legacy DMA resource and eats
>> up a fair chunk of that. Again, not an issue on modern hardware, but
>> ..
>>
>> > I believe that reserving everything below 1M after the real mode trampoline
>> > is allocated reduces amount of hidden dependencies and makes things simpler
>> > overall.
>>
>> Simpler, perhaps, and _I_ personally don't care about about 512kB of
>> memory any more on any machines I have, but ..
>
>Let's see if Sasha can dig out something... CCed.
>
>@Sasha, can you figure out who we can talk to whether Windoze reserves
>the first megabyte of memory unconditionally?

That's a great question, but I can't help there anymore :)

Adding James Morris...

-- 
Thanks,
Sasha