As stated in the summary, the nv driver - version 2.1.12 - fails to work with my new graphics card, a GeForce 9400 GT with PCI ID 10de:0641. On both Mandriva and Fedora, the system hangs at a black screen when X tries to run: it's not even possible to switch to a VT. So I can't give you any logs.
This is rather important, as it breaks Fedora 10 installation - see https://bugzilla.redhat.com/show_bug.cgi?id=480393 - because Fedora automatically tries to use the 'nv' driver during installation. So when booting the installer you just get the first few bits, then a black screen.
Interestingly, I can confirm something that I saw in a similar report: if you first run X with the proprietary driver, *then* switch to nv, it works. But from a cold boot, it fails. So I concur with that reporter that there's some kind of initialization of the card that the proprietary driver does correctly, that then allows nv to work.
Further: when booting clean to nv, Xorg.0.log is a 0-byte file, so no useful information there. Ben Skeggs is looking at this.
The mmiotrace of the proprietary driver starting up, that Ben requested from me via email, can be found at:
Should be working in 2.1.18
on May 28, 2016 at 05:54:06.
(provided by the Example extension).