linux-kernel - Re: [PATCH] [4/7] Don't use large pages to map the first 2/4MB of memory

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Message-ID: <alpine.LFD.1.00.0803211859410.3781@apollo.tec.linutronix.de>
Date:	Fri, 21 Mar 2008 19:03:19 +0100 (CET)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Andi Kleen <andi@...stfloor.org>
cc:	andreas.herrmann3@....com, mingo@...e.hu,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] [4/7] Don't use large pages to map the first 2/4MB of
 memory

On Fri, 21 Mar 2008, Andi Kleen wrote:
> > Also we split the first GB mapping anyway due to the various regions
> > (NX, RO, UC) in there.
> 
> I didn't think so unless you have DEBUG_RODATA enabled? 

NX is independent of DEBUG_RODATA and the RODATA protection should be
made unconditional on anyway.

> Also there
> should be no UC region there as known by the kernel. There might
> be a WC region there from the frame buffer code, but that is an MTRR,
> not a pageattr.

The first ioremap of the PCI space splits the GB page as well.

Thanks,

	tglx
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