linux-kernel - RE: [PATCH] To crash dump, we need keep other memory type except E820_RAM, because other type come from BIOS or firmware is used by other code(for example: PCI

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Message-ID: <88DC34334CA3444C85D647DBFA962C270FD7EB0B@SHSMSX102.ccr.corp.intel.com>
Date:	Wed, 31 Oct 2012 03:39:21 +0000
From:	"Zhang, Jun" <jun.zhang@...el.com>
To:	"H. Peter Anvin" <hpa@...or.com>
CC:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"x86@...nel.org" <x86@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"Fleming, Matt" <matt.fleming@...el.com>,
	Paul Gortmaker <paul.gortmaker@...driver.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] To crash dump, we need keep other memory type except
 E820_RAM, because other type come from BIOS or firmware is used by other
 code(for example: PCI_MMCONFIG).

Hello, Anvin
Thanks!

Hello, all
Next is my the latest version, please review it. 
Thanks!

>From 141546c77ff7be523a9e72f5259df4a6827f2c1a Mon Sep 17 00:00:00 2001
From: jzha144 <jun.zhang@...el.com>
Date: Wed, 31 Oct 2012 08:51:18 +0800
Subject: [PATCH] If we are doing a crash dump, we still need non-E820_RAM
 memory type address information, which come from BIOS or
 firmware. for example: PCI_MMCONFIG check this address.

Signed-off-by: jzha144 <jun.zhang@...el.com>
---
 arch/x86/kernel/e820.c |    9 +++++++++
 1 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index df06ade..f8672d0 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -851,6 +851,15 @@ static int __init parse_memmap_opt(char *p)
 		 * reset.
 		 */
 		saved_max_pfn = e820_end_of_ram_pfn();
+
+		/*
+		 * If we are doing a crash dump, we still need non-E820_RAM
+		 * memory type address information. so we only remove
+		 * E820_RAM type.
+		 */
+		e820_remove_range(0, ULLONG_MAX, E820_RAM, 1);
+		userdef = 1;
+		return 0;
 #endif
 		e820.nr_map = 0;
 		userdef = 1;
-- 
1.7.6


Best Regards!

Jun Zhang
Inet: 8821-4273
Dir.Tel: 86-21-6116-4273
Email: jun.zhang@...el.com


-----Original Message-----
From: H. Peter Anvin [mailto:hpa@...or.com] 
Sent: Wednesday, October 31, 2012 10:47 AM
To: Zhang, Jun
Cc: Thomas Gleixner; Ingo Molnar; x86@...nel.org; Andrew Morton; Fleming, Matt; Paul Gortmaker; linux-kernel@...r.kernel.org
Subject: Re: [PATCH] To crash dump, we need keep other memory type except E820_RAM, because other type come from BIOS or firmware is used by other code(for example: PCI_MMCONFIG).

On 10/30/2012 06:26 PM, Zhang, Jun wrote:
> From aebc336baa7ec2d4ccb6f21166770c7d2ee26cba Mon Sep 17 00:00:00 2001
> From: jzha144 <jun.zhang@...el.com>
> Date: Wed, 31 Oct 2012 08:51:18 +0800
> Subject: [PATCH] To crash dump, we need keep other memory type except  
> E820_RAM, because other type come from BIOS or firmware is  used by 
> other code(for example: PCI_MMCONFIG).

I'm sorry, I can't quite parse the description or the comment... could you clarify it a bit?  I think I know what you mean, but there is clearly risk for misunderstandings.

	-hpa

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