Re: Two Nvidia cards, and black screen

[<ce...@ri...>]

han...@sa... a =E9crit :
> I have 1 NVIDIA Gefore FX 5200 PCI, and one NVIDIA Gefore 6600 PCI-E=20
> card. I have both X servers set up correctly so that they run without=20
> any problem seperatly (with different keyboards and mice). Both X=20
> servers use the nvidia close source 6629 driver.
>=20
> My problem is that whenever I try to start the second X server, while=20
> the first one is already running, the monitor connected to the first X=20
> server goes black (monitor is turned off/signal lost). The xserver=20
> itself however continues running, and all applications (like music from=
=20
> xmms) also continue running. There are no errors in any log files. Ther=
e=20
> is no difference when trying to start the X servers in the opposite=20
> order. Starting the second X server always kills the display of the one=
=20
> already running.

Your problem looks similar to the one encountered with radeon cards.
Except you state that the first display is turned off without vga
signal. A Radeon card keeps the VGA signal up but the display is black=20
and can be restored by video mode switching (Ctrl-Alt-+/-).

In your case, without VGA signal, it shouldn't be possible to restore
the display but you could check just in case.

As explained in my previous mail, the problem occurs when the second
card do VGA IOs at initialization. Regarding the open source driver
those functions are provided by the vgahw module (see
http://www.x.org/X11R6.8.2/doc/DESIGN19.html for details). The log=20
entries are shown below:

(II) Loading sub module "vgahw"
(II) LoadModule: "vgahw"
(II) Loading /usr/X11R6/lib/modules/libvgahw.a
(II) Module vgahw: vendor=3D"X.Org Foundation"
         compiled for 6.8.2, module version =3D 0.1.0
         ABI class: X.Org Video Driver, version 0.7
(II) RADEON(0): vgaHWGetIOBase: hwp->IOBase is 0x03d0, hwp->PIOOffset is=20
0x0000

I don't know if the close source nvidia driver uses this module or
access the VGA registers by itself. Anyway the only solution is to
modify the driver to disable VGA IOs.

This has been done with the "VGAAccess" option for radeon and rage128=20
drivers in the following patches posted in the xorg bugzilla:
https://bugs.freedesktop.org/show_bug.cgi?id=3D2064
https://bugs.freedesktop.org/show_bug.cgi?id=3D2089

Regarding nvidia, you might ask them to implement this feature in their
driver.

Regards,
C=E9dric