Re: [GIT PULL] x86/urgent for v5.13-rc5

[Andy Lutomirski]

On Tue, Jun 8, 2021, at 10:53 AM, Michael Kelley wrote:
> From: James Morris <jmorris@xxxxxxxxx> Sent: Monday, June 7, 2021 11:47 AM
>> 
>> On Sun, 6 Jun 2021, Sasha Levin wrote:
>> 
>> > >
>> > >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...
>> 
>> Adding Michael Kelley.
>> 
>
> I checked with the Windows team.  Peter Anvin's statement from 11
> years ago is true.  On Intel and AMD processors, Windows unconditionally
> reserves the 1st megabyte of memory, minus one page used for real
> mode startup.   This is done to work around BIOS bugs.

Sorry to dredge up old skeletons.  Do you know *where* Windows allocates that one page used for real mode startup?  The current code in Linux has some bugs allocating that page, and it would be nice to sort it out.