I've added a couple of printk's to the AMD 760 AGP and into the AGPGART.
As far as I can see, amd-k7-agp does call the agp_add_bridge, which in turn, calls the inter_module_register function. (which registers the drm_agp.)
The nvidia driver inter_module_get_request should not fail!!!
What the **** am I missing here?!?!? Argh!
More on that later...
Found the source of one problem (after printk'ing it to death
): when I manually load the amd-k7-agp driver, the backend is being called and inter_module_get_request returns a valid pointer.
Now remains the second problem "couldn't find pre-allocated memory".
Looking into it now...
Things just got worse.
Uninstalled the drivers, tried reverting to the old configuration (2.6.0, 44.96/minion.de) and I'm getting the same problem.
I'm getting a new error before the "couldn't find pre-allocated memory" error
NV: bad offset / length into frame buffer: 0x0 0xff00000 0x4000000
Lesson to self, setup a second 2.6 machine to act as a guinea pig, before blowing the main production workstation