lspci vs nvidia-smi vs nvidia-xconfig reporting different PCI BusId

Hi,

I have two Nvidia 1080Ti’s connected via SLI in PCIex16 slots however different tools report different BusIDs (see examples below). Despite the kernel listing the cards at IDs 17 and 65, they only work with X if xorg.conf is configured with BusIDs 23 or 101 (the BUSIds as reported by nvidia-xconfig). I don’t understand why the IDs are different when reported by different tools. Please could someone explain?

My system: Asus TOF X299 Mark 2 motherboard, Intel i9 12 core, 64Gb Ram, 2 x EVGA Nvidia 1080Ti’s in PICe x16 slots 1 and 2 (connected by SLI).
I have upgraded the motherboard bios to the latest version, tried linux kernels 4.15.35, 4.15.36 and 4.18.8, and NVIDIA drivers 390.87, 396.54 and 410.48. They all exhibit the same problem. And ideas welcome please!

Luckily, the cards appear to work fine if configured on the higher BUSIDs 23/101!

Many thanks.

~$ lspci | grep NVIDIA
17:00.0 VGA compatible controller: NVIDIA Corporation GP102 [GeForce GTX 1080 Ti] (rev a1)
17:00.1 Audio device: NVIDIA Corporation GP102 HDMI Audio Controller (rev a1)
65:00.0 VGA compatible controller: NVIDIA Corporation GP102 [GeForce GTX 1080 Ti] (rev a1)
65:00.1 Audio device: NVIDIA Corporation GP102 HDMI Audio Controller (rev a1)
~$ nvidia-smi
Fri Sep 28 09:41:17 2018       
+-----------------------------------------------------------------------------+
| NVIDIA-SMI 410.48                 Driver Version: 410.48                    |
|-------------------------------+----------------------+----------------------+
| GPU  Name        Persistence-M| Bus-Id        Disp.A | Volatile Uncorr. ECC |
| Fan  Temp  Perf  Pwr:Usage/Cap|         Memory-Usage | GPU-Util  Compute M. |
|===============================+======================+======================|
|   0  GeForce GTX 108...  Off  | 00000000:17:00.0 Off |                  N/A |
|  0%   27C    P8     8W / 250W |      2MiB / 11178MiB |      0%      Default |
+-------------------------------+----------------------+----------------------+
|   1  GeForce GTX 108...  Off  | 00000000:65:00.0  On |                  N/A |
|  5%   49C    P8    20W / 250W |    604MiB / 11175MiB |      2%      Default |
+-------------------------------+----------------------+----------------------+
~$ nvidia-xconfig --query-gpu-info
Number of GPUs: 2

GPU #0:
  Name      : GeForce GTX 1080 Ti
  UUID      : GPU-f5cc3221-2f9e-ffeb-4608-f68a49579398
  PCI BusID : PCI:23:0:0

  Number of Display Devices: 1

  Display Device 0 (TV-1):
      EDID Name             : Acer K272HL
      Minimum HorizSync     : 31.000 kHz
      Maximum HorizSync     : 83.000 kHz
      Minimum VertRefresh   : 56 Hz
      Maximum VertRefresh   : 76 Hz
      Maximum PixelClock    : 170.000 MHz
      Maximum Width         : 1920 pixels
      Maximum Height        : 1080 pixels
      Preferred Width       : 1920 pixels
      Preferred Height      : 1080 pixels
      Preferred VertRefresh : 60 Hz
      Physical Width        : 600 mm
      Physical Height       : 340 mm


GPU #1:
  Name      : GeForce GTX 1080 Ti
  UUID      : GPU-82835edd-7125-c523-04af-a061d02e5e65
  PCI BusID : PCI:101:0:0

  Number of Display Devices: 2

  Display Device 0 (TV-1):
      EDID Name             : Acer K272HL
      Minimum HorizSync     : 31.000 kHz
      Maximum HorizSync     : 83.000 kHz
      Minimum VertRefresh   : 56 Hz
      Maximum VertRefresh   : 76 Hz
      Maximum PixelClock    : 170.000 MHz
      Maximum Width         : 1920 pixels
      Maximum Height        : 1080 pixels
      Preferred Width       : 1920 pixels
      Preferred Height      : 1080 pixels
      Preferred VertRefresh : 60 Hz
      Physical Width        : 600 mm
      Physical Height       : 340 mm

  Display Device 1 (TV-4):
      EDID Name             : BenQ EL2870U
      Minimum HorizSync     : 135.000 kHz
      Maximum HorizSync     : 135.000 kHz
      Minimum VertRefresh   : 40 Hz
      Maximum VertRefresh   : 60 Hz
      Maximum PixelClock    : 600.000 MHz
      Maximum Width         : 3840 pixels
      Maximum Height        : 2160 pixels
      Preferred Width       : 3840 pixels
      Preferred Height      : 2160 pixels
      Preferred VertRefresh : 60 Hz
      Physical Width        : 620 mm
      Physical Height       : 340 mm

nvidia-bug-report.log.gz (1.52 MB)

xorg.conf takes decimal values, lspci displays hex values
65 hex = 101 dec

Thanks generix - that’s ruined my day for being so obvious in retrospect!