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

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Date:	Tue, 19 Feb 2008 21:59:26 +0000
From:	Ian Campbell <ijc@...lion.org.uk>
To:	Joel Becker <Joel.Becker@...cle.com>
Cc:	Jeremy Fitzhardinge <jeremy@...p.org>,
	Jody Belka <lists-lkml@...b.org>, linux-kernel@...r.kernel.org,
	Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Andi Kleen <andi@...stfloor.org>,
	Mika Penttila <mika.penttila@...umbus.fi>
Subject: Re: 2.6.25-rc1 xen pvops regression


On Mon, 2008-02-18 at 02:40 -0800, Joel Becker wrote:
> On Sun, Feb 17, 2008 at 06:49:21PM +0000, Ian Campbell wrote:

> > x86/xen: Do not scan for DMI unless the DMI region is reserved by e820.

> 	This fixed it.  I'm now booting successfully.  Thank you!

Excellent. Jeremy, are you happy for this to go in?

>>From 23e4ec12b95064320f83fca1cc1ad5c7b2eb3386 Mon Sep 17 00:00:00 2001
From: Ian Campbell <ijc@...lion.org.uk>
Date: Tue, 19 Feb 2008 21:57:45 +0000
Subject: [PATCH] x86/xen: Do not scan for DMI unless the DMI region is reserved by e820.

Under Xen the memory at 0xf0000 is regular RAM and so can potentially contain a
page table and hence cannot be mapped. The e820 map given to guest reflects
this.

Signed-off-by: Ian Campbell <ijc@...lion.org.uk>
---
 drivers/firmware/dmi_scan.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/drivers/firmware/dmi_scan.c b/drivers/firmware/dmi_scan.c
index 653265a..7d29403 100644
--- a/drivers/firmware/dmi_scan.c
+++ b/drivers/firmware/dmi_scan.c
@@ -7,6 +7,7 @@
 #include <linux/bootmem.h>
 #include <linux/slab.h>
 #include <asm/dmi.h>
+#include <asm/e820.h>
 
 static char dmi_empty_string[] = "        ";
 
@@ -371,6 +372,9 @@ void __init dmi_scan_machine(void)
 		}
 	}
 	else {
+		if (!e820_all_mapped(0xF0000, 0xF0000+0x10000, E820_RESERVED))
+			goto out;
+
 		/*
 		 * no iounmap() for that ioremap(); it would be a no-op, but
 		 * it's so early in setup that sucker gets confused into doing
-- 
1.5.4.2

-- 
Ian Campbell

After the game the king and the pawn go in the same box.
		-- Italian proverb

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