Date: Tue, 13 Oct 2009 15:49:43 +0100
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Arjan van de Ven <arjan@infradead.org>
Cc: Ingo Molnar <mingo@elte.hu>, Siarhei Liakh <sliakh.lkml@gmail.com>,
       linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org,
       James Morris <jmorris@namei.org>,
       Andrew Morton <akpm@linux-foundation.org>, Andi Kleen <ak@muc.de>,
       Rusty Russell <rusty@rustcorp.com.au>,
       Thomas Gleixner <tglx@linutronix.de>, "H. Peter Anvin" <hpa@zytor.com>,
       David Howells <dhowells@redhat.com>, Aristeu Rozanski <aris@redhat.com>
Subject: Re: [PATCH V5] x86: NX protection for kernel data
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> I'd be surprised if anything ever did; this is the *kernel* mapping of
> the first megabyte, not some userspace mapping....

APM, BIOS32, EDD, PnPBIOS ..

However except for APM (which isn't generally needed on NX capable
devices or found on them) none of them are usually on critical paths
because EDD is just grovelling around sort of stuff, and BIOS32 isn't
generally used by the kernel anyway so could probably cope with flipping
the permissions on the low 1 MB each call.
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