vgapci0: <VGA-compatible display> port 0xef00-0xef7f mem 0xf5000000-0xf5ffffff,0xf2000000-0xf3ffffff irq 16 at device 0.0 on pci1
nvidia0: <Quadro NVS 135M> on vgapci0
vgapci0: child nvidia0 requested pci_enable_busmaster
vgapci0: child nvidia0 requested pci_enable_io
vgapci0: 0x10000000 bytes of rid 0x14 res 3 failed (0, 0xffffffffffffffff).
nvidia0: NVRM: NVIDIA MEM resource alloc failed, BAR1 @ 0x14.
nvidia0: NVRM: NVIDIA hardware alloc failed.
device_attach: nvidia0 attach returned 6
The kernel fails to set up the resources for the GPU's BAR1. It would be good to check that the SBIOS assigned reasonable memory ranges to all of the GPU's BARS, and set up the upstream bridges correctly. For what it's worth, 0x10000000 bytes (256MB) is reasonable for BAR1, but the resources printed in the first line of the above output seem to include only BAR0 (16MB) and BAR2 (32MB).