I will try to explain it in a different way.
- The “No bootable device” issue is known for a long time. You can find reference about that in this github issue: AppVM with GPU pass-through crashes when more than 3.5 GB (3584MB) of RAM is assigned to it · Issue #4321 · QubesOS/qubes-issues · GitHub
- To avoid this issue, for the “max-ram-below-4g” stubdom patch — only the stubdom patch method — the patch is only applied if the qube name start with “gpu_” Create a Gaming HVM
So if you use the xen.xml patch, you don’t have this difference between qube name starting with “gpu_”
If you want to use HVM using large amount of ram — with and without GPU passthrough —, you need to have this difference between qube named “gpu_” …
The guide Create a Gaming HVM can be improved:
- If you have time, xen.xml patch could be modified to only apply the patch if the qube name start with “gpu_”. It would be better because both stubdom patch method and xen.xml patch method would result in the same behavior regarding the “gpu_” naming thing
- The comment on github mentionning the “No Bootable device” could be linked + copy-pasted to make it more explicit
- If someone have a lot of time, it could maybe be possible to automatically decide to apply the patch or not by searching on how you can grep the pci devices list passed to the vm looking for something like NVIDIA/AMD/VGA/…