[libvirt] QEMU capabilities vs machine types

[Michal Privoznik]

Dear list,

I've ran into the following bug [1]. The problem is, even though we
check whether memory-backend-{ram,file} devices are supported, qemu
fails to start. As I see it, on one hand, qemu lies about supported
devices (when I imitated libvirt capabilities check by hand on the
command line). But on the other hand, libvirt is using '-M none' so even
if qemu is fixed, the domain would be unable to start anyway.

So I believe my question is, does anybody have a bright idea how to fix
this? I don't think we want to extend our capabilities from a list to a
matrix (where a machine type would select a list). Moreover, querying
and creating the matrix would take ages. But then again, machine type is
important. Maybe not so for -x86_64 but for -arm definitely! Or?

Michal

1: https://bugzilla.redhat.com/show_bug.cgi?id=1191567