weird failure mode on missing device (with solution)

[Thomas Klausner <wiz%NetBSD.org@localhost>]

Hi!

After a mainboard replacement, X wouldn't start (with the same
graphics card).

The error message was just
...
        CAICOS, CAICOS, CAICOS, CAICOS, CAICOS, CAICOS, CAICOS, ARUBA, ARUBA,
        ARUBA, ARUBA, ARUBA, ARUBA, ARUBA, ARUBA, ARUBA, ARUBA, ARUBA, ARUBA,
        ARUBA, ARUBA, ARUBA, ARUBA, ARUBA, ARUBA, ARUBA, ARUBA, ARUBA, ARUBA,
        ARUBA, ARUBA
[   796.350] (--) Using wscons driver on /dev/ttyE4 in pcvt compatibility mode 
(version 3.32)
[   796.350] (--) using VT number 5

[   796.354] (EE) No devices detected.
[   796.354]

So no real error in Xorg.0.log.

The problem turned out to be that on the new mainboard, the card was
suddenly on pci9:
vga0 at pci9 dev 0 function 0: vendor 0x1002 product 0x9498 (rev. 0x00)

and I had no /dev/pci9 device (only up to /dev/pci7).
Creating the device made X work again:

        ARUBA, ARUBA
[  4813.778] (--) Using wscons driver on /dev/ttyE4 in pcvt compatibility mode 
(version 3.32)
[  4813.778] (--) using VT number 5

[  4813.781] (II) Loading /usr/X11R7/lib/modules/drivers/radeon_drv.so
[  4813.781] (WW) VGA arbiter: cannot open kernel arbiter, no multi-card support


So far, this is documentation in case someone else stumbles over this problem :)

My question for today: can we improve the error handling here?
 Thomas