linux-kernel - Re: [PATCH] reserve end-of-conventional-memory to 1MB on 32-bit

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Message-Id: <1204324010.2610.1239905639@webmail.messagingengine.com>
Date:	Fri, 29 Feb 2008 23:26:50 +0100
From:	"Alexander van Heukelum" <heukelum@...tmail.fm>
To:	"Mark McLoughlin" <markmc@...hat.com>
Cc:	"Alexander van Heukelum" <heukelum@...lshack.com>,
	"Ingo Molnar" <mingo@...e.hu>, "Ian Campbell" <ijc@...lion.org.uk>,
	"H. Peter Anvin" <hpa@...or.com>, "Andi Kleen" <ak@...e.de>,
	"Thomas Gleixner" <tglx@...utronix.de>,
	"Jeremy Fitzhardinge" <jeremy@...p.org>,
	"LKML" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] reserve end-of-conventional-memory to 1MB on 32-bit

On Fri, 29 Feb 2008 22:06:59 +0000, "Mark McLoughlin"
<markmc@...hat.com> said:
> On Fri, 2008-02-29 at 19:38 +0100, Alexander van Heukelum wrote:
> > My first guess is that the BIOS data area is completely non-existent for
> > Xen. Is it guaranteed that the memory is zeroed out on boot?
> 
> Yep, that seems to be the case
> 
> > In that case we can special-case it easily:
> > 
> > change:
> >         /* Paranoia: should never happen, but... */
> >         if (lowmem >= 0x100000)
> >                 lowmem = 0xa0000;
> > 
> > into:
> >         /* Strange case, like Xen ;) */
> >         if (lowmem == 0 || lowmem >= 0x100000)
> >                 lowmem = 0x9f000;
> > 
> > Can you test that?
> 
> Yes, that fixes boot for me.

Thanks for testing this.

I'ld rather not count on Xen providing zeroed memory, though. I'll
try to find a different solution. It's weekend anyhow ;).

Greetings,
    Alexander
-- 
  Alexander van Heukelum
  heukelum@...tmail.fm

-- 
http://www.fastmail.fm - Or how I learned to stop worrying and
                          love email again

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