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Aqualung

Member

Registered: 2025-09-07

Posts: 23

Vulkan does not detect eGPU

LGGram laptop hooked up to Thunderbolt 5 (TB5) docking station via Thunderbolt 4 (TB4) port. TB5 eGPU enclosure hooked up to docking station. eGPU enclosure contains Intel Arc B580 GPU. Vulkan fails to detect Arc B580: it doesn't show up in, among others, vulkaninfo:

[dad@DadsGram Workspace]$ MESA_VK_DEVICE_SELECT=list vulkaninfo
selectable devices:
  GPU 0: 8086:a7a0 "Intel(R) Iris(R) Xe Graphics (RPL-P)" integrated GPU 0000:00:02.0

Any idea what I may be doing wrong? Here's some other debugging info:

[dad@DadsGram ~]$ lspci | grep VGA
00:02.0 VGA compatible controller: Intel Corporation Raptor Lake-P [Iris Xe Graphics] (rev 04)
41:00.0 VGA compatible controller: Intel Corporation Battlemage G21 [Arc B580]

[dad@DadsGram ~]$ lshw
...
*-display
     description: VGA compatible controller
     product: Raptor Lake-P [Iris Xe Graphics]
     vendor: Intel Corporation
     physical id: 2
     bus info: pci@0000:00:02.0
     logical name: /dev/fb0
     version: 04
     width: 64 bits
     clock: 33MHz
     capabilities: vga_controller bus_master cap_list rom fb
     configuration: depth=32 driver=i915 latency=0 resolution=2560,1600
     resources: iomemory:600-5ff iomemory:400-3ff irq:211 memory:603c000000-603cffffff memory:4000000000-400fffffff ioport:2000(size=64) memory:c0000-dffff memory:4010000000-4016ffffff memory:4020000000-40ffffffff
...
*-display
     description: VGA compatible controller
     product: Battlemage G21 [Arc B580]
     vendor: Intel Corporation
     physical id: 0
     bus info: pci@0000:41:00.0
     version: 00
     width: 64 bits
     clock: 33MHz
     capabilities: vga_controller bus_master cap_list rom
     configuration: driver=xe latency=0
     resources: irq:0 memory:52000000-52ffffff

Interestingly, no such thing happens when connecting eGPU directly to laptop's second TB4 port. (There's other funny stuff that happens in that scenario, though Vulkan does detect both GPUs just fine; see also discussions here and here.)

Last edited by Aqualung (2025-10-16 20:04:07)

unixman

Member

Registered: 2015-03-12

Posts: 128

Re: Vulkan does not detect eGPU

hi. Raptor Lake have additional "fb" cap. not sure what it means.
Manually edit icd json file put Battemage   IDs there.
is Battemage needs some exclusive kernel/mesa driver to enable vulkan or HW actually support vulkan?

Blacklist Raptor via kernel or some other means force Batlemage.

Last edited by unixman (Yesterday 17:12:57)

Aqualung

Member

Registered: 2025-09-07

Posts: 23

Re: Vulkan does not detect eGPU

Manually edit icd json file put Battemage   IDs there.

Thanks. I got two .json files in there: intel_hasvk_icd.x86_64.json and intel_icd.x86_64.json; in which of these should I put the Battlemage? And what would the precise syntax be?

is Battemage needs some exclusive kernel/mesa driver to enable vulkan or HW actually support vulkan?

I am pretty sure I got all the ancillary Vulkan software installed, and then some.

Here's a new development: sometimes after reboot, both GPUs show up. Sometimes only the integrated GPU does, and it looks like this is pretty random.

Blacklist Raptor via kernel or some other means force Batlemage.

I don't really want to do that, frankly.

unixman

Member

Registered: 2015-03-12

Posts: 128

Re: Vulkan does not detect eGPU

... sometimes both GPUs show up. ... I don't really want to do that, frankly.

So drivers is there, OK.

MESA_VK_DEVICE_SELECT=Battlemage_pciID  put there battle pci ID.
MESA_VK_DEVICE_SELECT_FORCE_DEFAULT_DEVICE=1

https://docs.mesa3d.org/envvars.html

which of these should I put the Battlemage?

move hasvk icd some other place leave other alone.
isn't icds contains pci/bus IDs? just replace that IDs.