Initializing fans about vendor-reset

[gnif]

I am sorry I did not intend to come across as aggressive. We do not re-post the VBIOS, we are returning the GPU to a state pre-system boot so the VM's BIOS can post the GPU's BIOS.

[9ary]

I understand the purpose of this module, there's no need to be so aggressive.

I don't really know what it takes to initialize the fans, but I do know that the VBIOS does it with no impact on the VM's ability to initialize the GPU. In fact, I don't have the "reset bug", my VM can boot and reboot as many times as I want without rebooting the host, as long as I don't let amdgpu touch the passthrough card (whether it's the host or a Linux VM). When shutting down, Windows leaves the fan off, and then I can start the VM again just fine.

Considering this, I thought it wouldn't be a problem to change the fan speed during reset, since the VBIOS obviously does it without loading firmware or initializing the GPU, it only does enough to get VGA emulation or UEFI GOP working during boot. I don't really want to put the GPU in a low power state, proper power management is much more complex and clearly out of scope. But doing something the VBIOS does didn't seem unreasonable to me. It can even be implemented behind a module parameter, which means it wouldn't break anything for anyone who doesn't touch it.

The only thing vendor-reset seems to add for me is the ability to boot a Windows VM after amdgpu has touched the card which I do not need. Unless of course I let amdgpu bind to the card to turn off the fan, but like I said, this doesn't seem like a good idea.

Anyway, thanks for answering my question, and sorry for wasting your time.

[gnif]

No, it's a reset, it's supposed to put the GPU into the pre-boot uninitialized state, that's is the entire purpose of this module.

[9ary]

How else would you suggest handling this then? You said it yourself, this module contains a large amount of code copy-pasted from amdgpu, and I don't think creating a third codebase that duplicates the same code for a minor QoL improvement would be very productive. I just want to turn the fan off, and I don't want to have a VM constantly running for that.

[gnif]

Perhaps a userspace tool. You're missing the point of this project though, it's not to put the GPU into a low power state, it's to prepare the GPU for re-use in a VM where the VM's driver will handle the specifics. If we init anything, when the VM tries to use it, it will not work. There is no way to detect VM shutdown/start vs VM reset.