I just committed big changes to the display branch (and I also merged latest trunk changes).
lstopo will now report things like this: PCI 10de:06d1 GPU L#0 ":0.0" GPU L#1 "cuda0" GPU L#2 "nvml0" The changes include: 1) We don't have a "display" specific OS device anymore, it's just another kind of GPU among cuda, opencl and nvml. The name is the X server display name. There are string attributes in these new GL GPU OS devices (lstopo -v): GPU L#9 (Backend=GL GPUVendor="NVIDIA Corporation" GPUModel="Tesla C2050") ":0.2" 2) The gl component is now buildable as a plugin 3) Given (2), we can't expose internal GL routines in the public API. So hwloc/gl.h is just made of inline helpers as any other hwloc/foo.h. It now contains functions to convert between displays (name or port/device) and hwloc OS devices: hwloc_obj_t hwloc_gl_get_display_osdev_by_port_device(hwloc_topology_t topology, unsigned port, unsigned device) hwloc_obj_t hwloc_gl_get_display_osdev_by_name(hwloc_topology_t topology, const char *name) int hwloc_gl_get_display_by_osdev(hwloc_topology_t topology, hwloc_obj_t osdev,unsigned *port, unsigned *device) If you really need the PCI device, just use osdev->parent as documented. If you need the locality, use hwloc_get_non_io_ancestor(topology, osdev)->cpuset See tests/gl.c for examples. Please review hwloc/gl.h and let me know if that works for you. I hope I used the words port/device/server/screen as expected. The last thing on my TODO list is to decide is whether we keep the "GL" name or switch to something among display/X11/X/... for filenames and function names. Brice