"Failed to allocate DMA push buffer" on 2.6.16.19 amd64 with 1.0-8762

[Johannes G]

Hi,
so far I failed to get a GeForce 7900 GTX (actually two of them for SLI...) running with XFree 4.3 on a Debian system. I already installed the latest driver 1.0-8762 and the kernel module is loaded.

However, starting the XServer aborts with:

(EE) NVIDIA(0): Unable to allocate DMA memory
(EE) NVIDIA(0): Push buffer DMA allocation failed
(EE) NVIDIA(0): *** Aborting ***
(EE) NVIDIA(0): Failed to allocate DMA push buffer
(EE) NVIDIA(0): *** Aborting ***

Also dmesg shows some errors:

NVRM: nv_kern_mmap: invalid offset: 0x00010000 @ 0x000000005a770000 (PCI)
NVRM: nv_kern_mmap: invalid offset: 0x00010000 @ 0x000000005acbf000 (PCI)

I attached the log from nvidia-bug-report.sh:
nvidia-bug-report.log


Any hints how to proceed?

Thanks in advance.

[zander]

Do the cards work if driven individually, i.e. is the problem SLI specific?

[Johannes G]

I did not expect SLI to be the problem, at least not at this early point of failure.
Nevertheless, I followed your hint and tried only one card -- without success. Also with only one card the XServer failed to start with the same error message (DMA push buffer)

[zander]

Please generate and attach an updated nvidia-bug-report.log file after trying to start X with only one of the GPUs.

[Johannes G]

OK, here it comes: nvidia-bug-report.log

[zander]

It looks like you're using a 32-bit X server on the 64-bit system and that the DMA push buffer's address is being truncated in the 32-bit NVIDIA X driver. Does the problem go away if you boot with e.g. mem=2G? If so, can you try if the attached workaround helps (w/o mem=??)? To apply the workaround and install the updated driver, please use:

# sh /path/to/NVIDIA-Linux-x86_64-1.0-8762-pkg2.run --extract-only
# cd NVIDIA-Linux-x86_64-1.0-8762-pkg2
# patch -p0 < /path/to/NVIDIA_kernel-1.0-8762-1476108.diff.txt
# cd usr/src/nv
# make clean install

This problem should be resolved in future NVIDIA Linux graphics driver releases.

[Johannes G]

It looks like you're using a 32-bit X server on the 64-bit system

True.

Does the problem go away if you boot with e.g. mem=2G?

Yes, the XServer started then.
Also after using your workaround by patching the driver everything worked fine -- even after reinstalling the second card.
Thanks a lot for your help!

Just a small question. Can you confirm that it is not possible to use TwinView and SLI at the same time?
If yes, is this a hardware limitation (e.g. there is only one compositing unit) or a lacking feature of the current drivers?

[nsheridan]

Hm, I have a similar problem. While booting with mem=2G fixes it, the supplied patch does not. Any suggestions greatly received.
bug-report attached.