linux-kernel - Re: [PATCH] Prevent reserving RAM in the region already reserved by BIOS

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Message-ID: <4BF46D9B.4090806@zytor.com>
Date:	Wed, 19 May 2010 16:00:43 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Mathieu Rondonneau <mathieu.rondonneau@...il.com>
CC:	Yinghai <yinghai.lu@...cle.com>, linux-kernel@...r.kernel.org,
	linux-arch@...r.kernel.org, Ingo Molnar <mingo@...e.hu>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH] Prevent reserving RAM in the region already reserved
 by 	BIOS

On 05/19/2010 03:58 PM, Mathieu Rondonneau wrote:
> Thanks for the feedback.
> 
> No, I don' t see any changes in the /proc/iomem.
> 
> I am trying to prevent a ioremap of a 4K size on a non aligned 4K
> address that is below the ISA_START_ADDRESS.
> 
> The problem generates a oops about overlapping.
> I have a fix which instruct to not to do any re-map if the section
> name is "reserved".
> Which is not really clean.
> I am looking for a clean way to tell the ioremap function to not remap
> bios reserved memory.
> That' s why I thought the e820 would be a good start.
> 
> I will continue looking into this. It does not crash the systems. A
> warning generates the oops.
> 

Why are you mapping a fixed-address in ISA space to begin with?

Requests to a fixed address (as opposed to dynamic allocation) have to
be granted even in reserved space -- after all, that's what the address
might be reserved for!

	-hpa
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