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References: <817ecb6f0907191742i13df19afmc4e258a857c3b465@mail.gmail.com>
	 <4A63C00A.2070805@zytor.com>
Date: Sun, 19 Jul 2009 21:02:47 -0400
Message-ID: <817ecb6f0907191802g4fd0970dj9e8327d44cf7e5a@mail.gmail.com>
Subject: Re: [PATCH] x86: Reducing footprint of BIOS32 service mappings
From: Siarhei Liakh <sliakh.lkml@gmail.com>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org,
       Arjan van de Ven <arjan@infradead.org>,
       Andi Kleen <andi@firstfloor.org>, Rusty Russell <rusty@rustcorp.com.au>,
       Ingo Molnar <mingo@elte.hu>, James Morris <jmorris@namei.org>,
       Andrew Morton <akpm@linux-foundation.org>, Andi Kleen <ak@muc.de>,
       Thomas Gleixner <tglx@linutronix.de>, linux-cris-kernel@axis.com,
       Roland Dreier <rdreier@cisco.com>
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For now I have only tested it on my home system and qemu. Actuallym in
both cases, I had to compile kernel with only CONFIG_PCI_GOBIOS=y,
since Kernel prefers other ways to access PCI when possible (with
CONFIG_PCI_GOANY=y).

On Sun, Jul 19, 2009 at 8:53 PM, H. Peter Anvin<hpa@zytor.com> wrote:
> Siarhei Liakh wrote:
>> According to BIOS32 specification
>> (http://members.datafast.net.au/dft0802/specs/bios32.pdf), at most two
>> pages per BIOS32 service should be set executable and no pages need to
>> be writeable. This patch modifies bios32_service() to set proper page
>> access permissions at time of service discovery, as described in the
>> specification.
>> Further, hardcoded protection of memory area between 640k to 1Mb have
>> been removed from static_protections(), since only pages mentioned
>> above need to be executable, not whole BIOS region.
>>
>> The patch have been developed for Linux 2.6.30 x86 by Siarhei Liakh
>> <sliakh.lkml@gmail.com> and Xuxian Jiang <jiang@cs.ncsu.edu>.
>>
>
> Specifications mean little in the BIOS space, unfortunately. ?Do we have
> any notion about how many machines this has been tested on?
>
> ? ? ? ?-hpa
>
> --
> H. Peter Anvin, Intel Open Source Technology Center
> I work for Intel. ?I don't speak on their behalf.
>
>
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