[vfio-users] What's the differences between different ways for gpu passthrough

[yimao]

Hi,

I'm a newbie and I have tried many ways to passthrough the gpu to the
guest. It works well but I found many guides is outdated. So I have
some questions.

1. How many ways to achieve the gpu passthrough nowadays, legacy vga
via seabios、non-vga(UEFI) via OVMF? What's the differences between
them?  Which one is the recommended way.
2. If I use legacy vga via seabios, should I apply the additional
kernel patches(acs override path、i915 vga arbiter patch)? Does these
patches will never be accepted by the upstream? So are there any linux
distribution applied these patches. Is the VFIO_PCI_VGA kernel config
necessary?
3. Which gpu passthrough method does ovirt、unraid and proxmox choose？
4. When we talk about primary/secondary GPU passthrough, what does
primary/secondary refer to, host gpu or guest gpu?

Thanks in advance
Yimao Yang.