linux-kernel - Re: 2.6.25-rc1 xen pvops regression

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Message-ID: <47BE08C0.5060700@zytor.com>
Date:	Thu, 21 Feb 2008 15:26:56 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Jeremy Fitzhardinge <jeremy@...p.org>
CC:	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Ian Campbell <ijc@...lion.org.uk>,
	Joel Becker <Joel.Becker@...cle.com>,
	Jody Belka <lists-lkml@...b.org>, linux-kernel@...r.kernel.org,
	Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	Andi Kleen <andi@...stfloor.org>,
	Mika Penttila <mika.penttila@...umbus.fi>
Subject: Re: 2.6.25-rc1 xen pvops regression

Jeremy Fitzhardinge wrote:
> 
> It seems to me that those pages are being handed out as heap pages by 
> the early allocator.  In the Xen case this is OK because there's nothing 
> magic about them.  But if real hardware doesn't reserve these pages in 
> the E820 map, then they could end up being used as regular memory by 
> mistake, which is an issue.
> 

No, they couldn't.

On real hardware they'll be memory types 0 or 2, depending on whether or 
not they're marked reserved.

Available RAM is type 1.

	-hpa
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