From mboxrd@z Thu Jan  1 00:00:00 1970
From: ludo@gnu.org (Ludovic =?utf-8?Q?Court=C3=A8s?=)
Subject: Re: poor scrolling in qemu-kvm
Date: Sat, 29 Nov 2014 21:53:54 +0100
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References: <CAKrPhPPXnAVw5U=yaee6iiFAHJ9rq2upqsp=MioRSshHSgopOw@mail.gmail.com>
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In-Reply-To: <CAKrPhPPXnAVw5U=yaee6iiFAHJ9rq2upqsp=MioRSshHSgopOw@mail.gmail.com>
	(Federico Beffa's message of "Sat, 29 Nov 2014 17:23:19 +0100")
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To: Federico Beffa <beffa@ieee.org>
Cc: Guix-devel <guix-devel@gnu.org>

Federico Beffa <beffa@ieee.org> skribis:

> Have someone found out the reason for this poor performance in
> qemu-kvm and how to fix it?

Yes, I eventually found out: by default, QEMU uses a Cirrus VGA graphics
adapter emulator, which is damn slow for this kind of framebuffer thing.

The right thing is to use =E2=80=98-vga std=E2=80=99, which uses a =E2=80=
=9Cstandard VGA=E2=80=9D
emulator, which doesn=E2=80=99t have this problem.

However, X will fail to start currently when using this.  The fix is to
use xf86-video-modesetting.  But this driver is not currently usable
because it requires a version of libdrm incompatible with that currently
used by xorg-server/MESA.

Long story short: we just need to update MESA to use the newer libdrm,
and we should be able to fix that.

Would you like to try?  :-)

Thanks,
Ludo=E2=80=99.