Hi, Yes, the stamp check was added. So the qemu emulator should return a suitable RSS BPF helper or nothing. Each qemu emulator may have a different helper that suits it. So, the idea is to ask for the helper from qemu.
On Tue, Aug 24, 2021 at 9:41 AM Markus Armbruster <arm...@redhat.com> wrote: > Andrew Melnichenko <and...@daynix.com> writes: > > > Hi, > > > >> The helper may or may not be installed at the path compiled into QEMU. > >> > > Yes, so the helper will not be called - QEMU will try to initiate eBPF > RSS > > or use "in-qemu" RSS. > > My point is: the proposed command's mission is to help the management > application run the right helper. However, its advice is *unreliable*. > It may point to the wrong helper, or to nothing at all. The right > helper may still exist elsewhere. > > I suspect you're trying to address the problem at the wrong level. > > Similar versioning issues exist with other helpers. We've been doing > fine without QEMU providing unreliable advice on where they might sit in > the file system. What makes this one different? > > >> What happens when you use the wrong helper? > >> > > UB - in most cases, eBPF program will work with wrong configurations. > > That's why the stamp was added. > > > > query-helper-paths checks the stamp only for RSS helper. > > I have no idea what you're talking about :) > > My best guess is that you're trying to tell me that attempting to work > with the wrong helper will fail cleanly due to some stamp check. That > would be nice. > >
