Created attachment 268374 [details]
dmesg from the machine in question.

On an EPYC 7003 series server with four identical Instinct MI50 GPUs, sysctl for hw.dri.0 and hw.dri.1 are created but hw.dri.2 and hw.dri.3 are not. Possibly causing the inability of the Vulkan loader to enumerate the devices.

/dev/dri/cardX and renderDX devices exist for all four cards, but vulkan is only able to load drivers for card0 and card1. dmesg shows two instances of "sysctl_add_oid: can't re-use a leaf (hw.dri.1.name).

# pciconf -lv
vgapci0@pci0:198:0:0:   class=0x030000 rev=0x00 hdr=0x00 vendor=0x1002 device=0x66a0 subvendor=0x1002 subdevice=0x081e
    vendor     = 'Advanced Micro Devices, Inc. [AMD/ATI]'
    device     = 'Vega 20 [Radeon Pro/Radeon Instinct]'
    class      = display
--
vgapci1@pci0:200:0:0:   class=0x030000 rev=0x41 hdr=0x00 vendor=0x1a03 device=0x2000 subvendor=0x1a03 subdevice=0x2000
    vendor     = 'ASPEED Technology, Inc.'
    device     = 'ASPEED Graphics Family'
    class      = display
--
vgapci2@pci0:131:0:0:   class=0x030000 rev=0x00 hdr=0x00 vendor=0x1002 device=0x66a0 subvendor=0x1002 subdevice=0x081e
    vendor     = 'Advanced Micro Devices, Inc. [AMD/ATI]'
    device     = 'Vega 20 [Radeon Pro/Radeon Instinct]'
    class      = display
--
vgapci3@pci0:67:0:0:    class=0x030000 rev=0x00 hdr=0x00 vendor=0x1002 device=0x66a0 subvendor=0x1002 subdevice=0x081e
    vendor     = 'Advanced Micro Devices, Inc. [AMD/ATI]'
    device     = 'Vega 20 [Radeon Pro/Radeon Instinct]'
    class      = display
--
vgapci4@pci0:3:0:0:     class=0x030000 rev=0x00 hdr=0x00 vendor=0x1002 device=0x66a0 subvendor=0x1002 subdevice=0x081e
    vendor     = 'Advanced Micro Devices, Inc. [AMD/ATI]'
    device     = 'Vega 20 [Radeon Pro/Radeon Instinct]'
    class      = display

The results are the same on 15-RELEASE and 16-CURRENT from early February 2026. Mesa-dri and mesa-devel drivers produce the same results.