problem with voodoo 3 and multiple X servers

[Erik Steffl <steffl@bigfoot.com>]

  I don't use multiple X servers too often but I think that since X 4.x 
there are some problems when running multiple X servers on same machine 
(voodoo 3 card).

  I have dri enabled, it works ok. as long as I run only one instance 
of X it works without any problems.

  the problem as manifested now is: I am running one X server (0) fvwm, 
it works without problems.

  I started another X server (1), runing kde and openoffice (started 
using startx from virtual console). from time to time it almost stops 
reacting, it doesn't update screen properly, only fonts are redrawn, the 
rest of the screen seems to be frozen (the effect is that the screen 
gets overwritten by text that seems to be slightly relevant to what 
should be going on, e.g. when I go to menu and this happens the menu is 
not updated anymore but near menu the menu item labels are redrawn (text 
only)).

 when I switch to another vt and back it works ok, for some time.

  it seems like everytime this happens the following message is printed 
on the console where X was started from:

Resetting FIFO

  googling revealed that some people had the same message printed when 
using xinerama, didn't find any resolution for that but not sure it's 
rlated.

  I also foound somewhat similar debian bug 164303, that one was closed 
because submitter said he found out that it's a hw problem...

  any ideas on what's going on or how to troubleshoot?

  system:

    debian unstable
    kernel 2.4.18 (with tdfx)
    ii  xserver-xfree8 4.2.1-4
    00:0f.0 VGA compatible controller: 3Dfx Interactive, Inc. Voodoo 3 
(rev 01)

  TIA!

	erik