linux-kernel - Re: Fwd: [PATCH] x86: Use larger chunks in mtrr

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Message-ID: <20150903024542.GS8051@wotan.suse.de>
Date:	Thu, 3 Sep 2015 04:45:42 +0200
From:	"Luis R. Rodriguez" <mcgrof@...e.com>
To:	Stuart Hayes <stuart.w.hayes@...il.com>
Cc:	tglx@...utronix.de, mingo@...hat.com,
	"H. Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org,
	x86@...nel.org, prarit@...hat.com, mcgrof@...not-panic.com,
	Toshi Kani <toshi.kani@...com>
Subject: Re: Fwd: [PATCH] x86: Use larger chunks in mtrr_cleanup

On Mon, Aug 31, 2015 at 11:05:33AM -0500, Stuart Hayes wrote:
> Increase the range of chunk sizes tried in mtrr_cleanup() so it is able
> to map large memory configs into MTRRs.
> 
> Currently, mtrr_cleanup() will fail with large memory configurations,
> because it limits chunk_size to 2GB, which means that each MTRR can only
> cover 2GB of memory.  With a memory size of, say, 256GB, and ten variable
> MTRRs (such as some recent Intel CPUs have), it is not possible to set up
> the MTRRs to cover all of memory.

Linux drivers no longer use MTRR so why is the cleanup needed, ie, what would
happen if the cleanup is just skipped in your case ?

  Luis
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