From: ebiederm@xmission.com (Eric W. Biederman)
To: Andi Kleen <ak@muc.de>
Cc: kraxel@suse.de, jsimmons@infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] Use MTRRs by default for vesafb on x86-64
Date: 16 May 2003 16:58:39 -0600 [thread overview]
Message-ID: <m1of2233ds.fsf@frodo.biederman.org> (raw)
In-Reply-To: <20030515145640.GA19152@averell>
Andi Kleen <ak@muc.de> writes:
> x86-64 cannot call the 32bit VESA BIOS. This means when vesafb is active
> it does software copying in the vesa frame buffer. This is insanely slow
> when the frame buffer is not marked for write combining.
>
> Some discussion showed that the use_mtrr flag was only off for some
> old broken ET4000 ISA card. x86-64 has no ISA, so this is no concern.
> Make the default depend on CONFIG_ISA.
>
> Patch for 2.5.69. Originally suggested by Gerd Knorr.
I don't know if this affects the frame buffers per se.
But often BIOS's on systems with large amounts of memory configure
overlapping mtrrs (where an uncacheable mtrr would override a larger
cacheable range). To date this has confused the linux mtrr code when
it tries to modify things, and you cannot properly setup mtrrs. I
believe this applies to both the fb case as well as X.
Eric
next prev parent reply other threads:[~2003-05-16 22:49 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-05-15 14:56 [PATCH] Use MTRRs by default for vesafb on x86-64 Andi Kleen
2003-05-15 15:16 ` Dave Jones
2003-05-15 15:20 ` Andi Kleen
2003-05-15 15:25 ` Dave Jones
2003-05-16 20:51 ` Alan Cox
2003-05-18 5:39 ` Andi Kleen
2003-05-18 16:11 ` Jamie Lokier
2003-05-18 20:40 ` Alan Cox
2003-05-18 22:34 ` Jamie Lokier
2003-05-18 22:52 ` Dave Jones
2003-05-18 23:33 ` Jamie Lokier
2003-05-19 0:02 ` Dave Jones
2003-05-19 0:28 ` Jamie Lokier
2003-05-19 1:24 ` Dave Jones
2003-05-16 22:58 ` Eric W. Biederman [this message]
2003-05-19 10:37 ` Andi Kleen
2003-05-19 12:26 ` Eric W. Biederman
-- strict thread matches above, loose matches on Subject: below --
2003-05-19 9:16 Etienne Lorrain
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