Runtime Error: No device at given index

[Blank517]

Laptop with
CPU: AMD Ryzen 7 3750H
GPU 0: NVIDIA GeForce GTX 1650
GPU 1: AMD Radeon RX Vega 10 Graphics

Logs:
memtest_vulkan.log

[galkinvv]

Do you have any vulkan apps working fine? Looks like the vulkan loader installed but no actual graphics driver installed.

However it seems to be a bug in memtest_vulkan that such situation is not handled in graceful way+message, thanks for reporting.

[Blank517]

I updated the radeon adrenaline drivers (i had a really old version) and now is working. But why it wasn't loading at the nvidia gpu before?

[galkinvv]

normally it multi-GPU system memtest_vulkan should suggest to select a GPU. If it still doesn't suggest using nvidia and uses only AMD - maybe your nvidia drivers are somehow problematic too in respect to vulkan support?

To check this - select nvidia GPU in bottom dropdown and then select vulkan in Advanced tab, like this

Make a screenshot after vulkan selection

[Blank517]

Yes it works for both gpus but after updating only the radeon driver. What I'm asking is why only after updating the radeon driver i could choose the nvidia gpu and not before.

Screenshot:

[galkinvv]

While I never seen such behaviour on windows, I seen once it on Linux. The reason is "buggy vulkan drivers, typically from the start of Vulkan 'era' that has severe bugs during device enumeration stage". Those severe bugs leads to the failure of enrire enumeration process. So application quering vulkan devices gets 0 results.

Note: normally each driver reports list of devices supported by it, so all installed drivers participate in the provess.

To workaround/ensure that this is really caused by a buggy driver - a special Environment variable VK_DRIVER_FILES can be used to limit search to a single json file decribing driver of a specific vendor, causing any vulkan application us only it.

However doing this is a bit cumbersome:

1. open GPU-Z, select the wanted GPU at bottom dropdown, switch to Advanced tab, resize windows to make it wiider - you should get visible the last digits of "Registry Path" being the GPU "4-digit-index" in the OS (corresponding just to order of driver installation, not to any hardware properties). Its 0001 on the example above
   
2. Open regedit, navigate to the "GPU devices list" registry key, replacing ???? with the just found number

   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class{4d36e968-e325-11ce-bfc1-08002be10318}\????

3. Scroll to VulkanDriverName entry, copy its value
4. create 2-line enforce_vulkan_vendor.bat in the folder containing memtest_vulkan, with setting VK_DRIVER_FILES to value copied above, like this for NVIDIA:

   SET VK_DRIVER_FILES=C:\windows\System32\DriverStore\FileRepository\nv_dispwi.inf_amd64_2c2e61b609af99d4\nv-vk64.json
   memtest_vulkan-v0.5.0.exe

   and run it. This way vulkan application will see and use only devices from a single vendor (possibly several if many GPUs from one vendor) but would not be affected by bugs in other vendor drivers. Note that the numbers in this example depend on a driver vesion, they would be different in different environments.
   
   4.1. AMD varinat looks like

   SET VK_DRIVER_FILES=C:\windows\System32\DriverStore\FileRepository\u0409016.inf_amd64_2b8774c9217183cc\B408421\amd-vulkan64.json

   
   4.2. Intel varinat looks like

   SET VK_DRIVER_FILES=C:\windows\System32\DriverStore\FileRepository\iigd_dch.inf_amd64_b53c057d22ce6f37\igvk64.json

[galkinvv]

I plan to impove error message for such situation in the future, so keeping this open.