Many X configuration options that take a display device name can also be qualified with a GPU. This is done by prepending one of the GPU's names to the display device name. For example, the "MetaModes" X configuration option can be used to enable display devices from multiple GPUs in SLI Mosaic or Base Mosaic configurations:
Option "MetaModes" "1280x1024 +0+0, 1280x1024 +1280+0"
You can use a display device name qualifier along with a GPU qualifier to configure which display should be picked and from which GPU. E.g.,
Option "MetaModes" "GPU-1.DFP-0:1280x1024 +0+0, GPU-0.DFP-0:1280x1024 +1280+0"
Other X configuration options that support GPU names include:
The description of each X configuration option in Appendix B, X Config Options provides more detail on the available syntax for each option.
To find all available names for your configuration, start the X
server with verbose logging enabled (e.g.,
startx -- -logverbose 5, or
enable the "ModeDebug" X configuration option with
nvidia-xconfig --mode-debug and
restart the X server).
The X log (normally /var/log/Xorg.0.log) will contain information regarding each GPU. E.g.,
(II) NVIDIA(0): NVIDIA GPU NVS 510 (GK107) at PCI:15:0:0 (GPU-0) (II) NVIDIA(0): VERBOSE: GPU UUID: GPU-758a4cf7-0761-62c7-9bf7-c7d950b817c6
Alternatively, nvidia-xconfig can be used to query the GPU
GPU #0: Name : NVS 510 UUID : GPU-758a4cf7-0761-62c7-9bf7-c7d950b817c6 PCI BusID : PCI:3:0:0
Each name has different properties that may affect which name is appropriate to use. The possible names are:
An NV-CONTROL target ID-based name (e.g., "GPU-0"). The NVIDIA X driver will assign a unique ID to each GPU on the entire X server. These IDs are not guaranteed to be persistent from one run of the X server to the next, so is likely not convenient for X configuration file use. It is more frequently used in communication with NV-CONTROL clients such as nvidia-settings.
An UUID-based name (e.g., "GPU-758a4cf7-0761-62c7-9bf7-c7d950b817c6"). This name is a SHA-1 hash, formatted in canonical UUID 8-4-4-4-12 format. This UUID is unique for each physical GPU, and will be the same regardless of where the GPU is connected.