Blank screen on X server startup with 256.35 using Quadro NVS 290 on F13 x86_64

[Kevin-B]

I'm running F13 for x86_64 on an Intel Xeon machine w/ 12GB memory. Kernel version is 2.6.33.6-147.fc13.x86_64. When starting the X server using the nvidia 256.35 driver, the screen goes blank, the keyboard goes dead, and the monitor enters power-save mode. When I connect from another machine, top shows me that the X server is using 100% cpu.

If I use akmod-nvidia-195.36.24-1.fc13.5.x86_64 from RPM Fusion, the problem does not occur. However, all later releases of akmod-nvidia from RPM Fusion cause the screen to go blank on startup. I fetched the SRPMs for the working akmod-nvidia and the next release up (which exhibited the blank screen on start-up problem). The only difference between these versions is the addition of the patch NVIDIA_kernel-195.36.24-6120611.diff.txt published by zander in the thread Intel-VT + 195.36.24 = Blank screen. Study of the 256.35 kernel module sources show that this patch is included there too. A reverse patch does not apply cleanly, however.

The patch below allows me to run 256.35 without getting the blank screen. This is definitely not a good fix, but will hopefully point someone in the right direction:

diff -upr ../../foo.sav/kernel/nv-linux.h ./nv-linux.h
--- ../../foo.sav/kernel/nv-linux.h	2010-06-16 18:42:59.000000000 -0700
+++ ./nv-linux.h	2010-07-17 17:10:49.000000000 -0700
@@ -344,7 +344,7 @@ int nv_acpi_uninit (void);
 #define NV_SG_MAP_BUFFERS 1
 extern int nv_swiotlb;
 
-#if defined(CONFIG_DMAR)
+#if 0 && defined(CONFIG_DMAR)
 #define NV_INTEL_IOMMU 1
 #else
 /*

I've also tried adding intel_iommu=igfx_on to the kernel command line, but that did not help.

Full bug report attached.

[Kevin-B]

The problem that I reported earlier still exists in 256.52.

I have found, however, that specifying "intel_iommu=off" on the kernel command line makes the problem go away. I would rather not have to do this though.