nixos/nvidia: update description of BusIds for caveats

Author: MakiseKurisu

nixos/modules/hardware/video/nvidia.nix

@@ -120,30 +120,48 @@ in
       prime.nvidiaBusId = lib.mkOption {
         type = busIDType;
         default = "";
-        example = "PCI:1:0:0";
+        example = "PCI:1@0:0:0";
         description = ''
           Bus ID of the NVIDIA GPU. You can find it using lspci; for example if lspci
-          shows the NVIDIA GPU at "01:00.0", set this option to "PCI:1:0:0".
+          shows the NVIDIA GPU at "0001:02:03.4", set this option to "PCI:2@1:3:4".
+
+          lspci might omit the PCI domain (0001 in above example) if it is zero.
+          In which case, use "@0" instead.
+
+          Please be aware that this option takes decimal address while lspci reports
+          hexadecimal address. So for device at domain "10000", use "@65536".
         '';
       };
 
       prime.intelBusId = lib.mkOption {
         type = busIDType;
         default = "";
-        example = "PCI:0:2:0";
+        example = "PCI:0@0:2:0";
         description = ''
           Bus ID of the Intel GPU. You can find it using lspci; for example if lspci
-          shows the Intel GPU at "00:02.0", set this option to "PCI:0:2:0".
+          shows the Intel GPU at "0001:02:03.4", set this option to "PCI:2@1:3:4".
+
+          lspci might omit the PCI domain (0001 in above example) if it is zero.
+          In which case, use "@0" instead.
+
+          Please be aware that this option takes decimal address while lspci reports
+          hexadecimal address. So for device at domain "10000", use "@65536".
         '';
       };
 
       prime.amdgpuBusId = lib.mkOption {
         type = busIDType;
         default = "";
-        example = "PCI:4:0:0";
+        example = "PCI:4@0:0:0";
         description = ''
           Bus ID of the AMD APU. You can find it using lspci; for example if lspci
-          shows the AMD APU at "04:00.0", set this option to "PCI:4:0:0".
+          shows the AMD APU at "0001:02:03.4", set this option to "PCI:2@1:3:4".
+
+          lspci might omit the PCI domain (0001 in above example) if it is zero.
+          In which case, use "@0" instead.
+
+          Please be aware that this option takes decimal address while lspci reports
+          hexadecimal address. So for device at domain "10000", use "@65536".
         '';
       };