On 2023/10/30 21:14, Yuri Benditovich wrote:
>
>
> On Mon, Oct 30, 2023 at 7:14 AM Akihiko Odaki <akihiko.odaki@daynix.com
> <mailto:akihiko.odaki@daynix.com>> wrote:
>
> vhost requires eBPF for RSS. When eBPF is not available, virtio-net
> implicitly disables RSS even if the user explicitly requests it. Return
> an error instead of implicitly disabling RSS if RSS is requested but not
> available.
>
>
> I think that suggesting RSS feature when in fact it is not available is
> not a good idea, this rather desinforms the guest.
> Existing behavior (IMHO) makes more sense.
> We can extend this discussion if needed, of course.
This change is not to advertise RSS when it's not available; it instead
reports an error to the user.
For example, think of the following command line:
qemu-system-x86_64 -device virtio-net,rss=on,netdev=n -netdev user,id=n
Before this change, it gives no error and the user will not know RSS is
not available. With this change it now gives an error as follows:
qemu-system-x86_64: -device virtio-net,rss=on,netdev=n: Can't load eBPF RSS
Does this mean failure to run QEMU if the RSS required in the command line and EBPF can't be loaded?
(for example if we run the system with kernel < 5.8)?
I'm not sure this is user-friendly behavior...