SOLVED Problem with X 4.2.1 and Matrox G400 dual-head setup

[Paul Mackinney <paul@mackinney.net>]

Thanks to Simon Hepburn and Sebastien Picard for their sapient replies.

Simon pointed out that I had mis-matched drivers, the mga_hal driver was
compiled for X4.1, not X4.2. Weird, because the driver either came from:
-The latest xfree86 deb
-The 4.2.0 drivers distributed by Matrox
-Compiled locally from the xfree 4.2.0 source
-Or perhaps the mga_hal driver came from somewhere else years ago and the deb
updates have been ignoring it. I notice that the xfree86 sources don't
contain an mga_hal driver...

The history is that my card had never worked in dual-head mode with the
xfree drivers, only with the Matrox ones. Every time apt upgrades Xfree,
I typically have to reinstall the Matrox package. But this time I
couldn't because their installer check versions and 4.2.1 was too high.

Simon's advice about creating a local X11 folder and using a ModulePath
line in the config file did the trick, I'll set it up outside the
DEBCONF section and hopefully be able to run apt without having to
reconfigure.

Simon Hepburn declaimed:
> From your log file:
> 
> (II) Loading /usr/X11R6/lib/modules/drivers/mga_hal_drv.o
> (II) Module mga_hal: vendor="The XFree86 Project"
>         compiled for 4.1.0, module version = 1.0.0
>         ABI class: XFree86 Video Driver, version 0.4
> (II) MGA(0): Matrox HAL module used
> 
> You are using a module compiled for X4.1 with X4.2. In the matrox tarball 
> there is a directory with modules compiled for X4.2.
> 
> BTW, I now ignore the matrox install instructions/script and put their stuff 
> under /usr/local/ and set a module path in XF86config-4:
> 
> simon@cromlech:~$ ls -l /usr/local/X11/matrox
> total 620
> -rw-r--r--    1 root     root       191465 Jan 23  2002 mga_drv.o
> -rw-r--r--    1 root     root       430682 Jan 23  2002 mga_hal_drv.o
> 
> simon@cromlech:~$ cat /etc/X11/XF86Config-4
> # XF86Config-4
> 
> Section "Files"
>         FontPath        "/var/lib/defoma/x-ttcidfont-conf.d/dirs/TrueType"
>         FontPath        "/usr/lib/X11/fonts/Type1"
>         FontPath        "/usr/lib/X11/fonts/misc/:unscaled"
>         ModulePath    "/usr/X11R6/lib/modules/"
>         ModulePath    "/usr/local/X11/matrox/"
> EndSection
> <snip>
> 
> The order of the ModulePath entries dictates which version (X4.2.1 or matrox) 
> of mga_drv.o you get to use with mga_hal_drv.o. Both work fine for me with a 
> G450. YMMV with a G400. I do things this way so as to avoid mucking about 
> with dir's that are under the control of the package management.
Specifically, my local folders are:

/usr/local/X11/matrox/dri/mga_dri.so
/usr/local/X11/matrox/drivers/mga_drv.o
/usr/local/X11/matrox/drivers/mga_hal_drv.o

All of these files came from the Matrox web site, the mga beta driver
package from Feb '02.