Multihead screen corruption

From: Louis Sabet (louis_at_mobiles.co.uk)
Date: 04/14/04 

Date: Wed, 14 Apr 2004 15:02:02 +0100

Hi all,

I'm having some fairly major problems with my 3-monitor setup. I'm running
the latest Gentoo, and the latest copies of all the major packages.

I've tried other versions to no avail, but currently I'm running:
kernel 2.6.4-r1 (gentoo-dev-sources)
XFree86 Version 4.3.0.1 (compiled on above)
No AGPGart or DRI anything in the kernel or anywhere else.
No framebuffer stuff in the kernel.

I have three graphics cards - all three are identical bog standard Matrox
G200 PCI cards with 4Mb RAM sitting in a Compaq AP400 twin processor PIII
machine.

An "X -configure" successfully creates a working XF86Config file which
works *most* of the time.

I've now spent too long trying to get this to be stable and am back at
square one - i.e. an XF86Config pretty much identical to the one I started
with, and monitors randomly corrupting overnight for no reason.

I can have three working monitors before leaving work, and when I get back
in the morning, the machine has completely frozen. A hard reboot reveals
that trying to launch X again causes monitor 0 to wake up and display what
it should, but the other monitors have a 20/80 chance of actually
displaying what they should. If they're misbehaving (which is more
likely), they'll weirdly be displaying whatever was on the screen before
the hard reboot (with a little corruption). As time goes on, these images
get more and more corrupted.

I don't know much about the intricacies of getting a picture onto a
monitor, but it sounds to me like the video ram isn't being cleared or
reset properly at some stage - anyone? Is there a way to force it to reset?

I can just about see that the mouse is active on these screens, as some of
the pixels move and change colour when I move the mouse, but that's about
all I get - oh, and the screensavers kick in and are also corrupted when
displayed on monitor 1 or 2 (remember 0 is always working).

I'd be happy to just ditch the three graphics cards and replace them with
newer/more reliable ones if I knew it was definitely down to the cards,
but I've already replaced them with a number of different matrox cards
(millennium II's, and AGP g200's) - all to no avail. Of course all these
still use the mga driver.

Also what I really don't understand is why
sometimes it works perfectly for a couple of days, and then I have to
spend ages messing about with graphics cards trying to get
it to work again. It seems to be that it only does this if it crashes.
Then I have a battle on my hands trying to get the graphics cards to
realise they're accepting a new picture now (not displaying some old
corrupted junk in RAM).

My XF86Config is here: http://www.mobiles.co.uk/louis/XF86Config

So anyway - I googled, and googled and googled some more, and couldn't
find anyone with the same problem - if anyone has any suggestions, I'd be
very glad to hear them!

Best Regards, and thanks in advance,

L

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