Hi, Looking at the code, it looks like that comment was written at a time where per-virtqueue MSIX interrupts were not available, and virtio_alloc_virtqueues() API was already designed to receive a flag to indicate that per-virtqueue MSIX interrupts were requested. The code you quoted would likely have been a simple placeholder, to be replaced with something like "flags |= VIRTIO_PERVQ_INTR" once the support had come. It's a very common pattern to start with setting flags = 0, and then bitwise or |= flags depending on the situation.
However: - per-virtqueue MSIX interrupts are now available (e.g. look at vtpci_setup_interrupts()), and - virtiqueues interrupt setup happens in a separate API, i.e. virtio_setup_intr(), which takes care all the possible cases So as far as I can tell that comment is not relevant anymore and can be removed together with the flags. Unless I'm wrong, ofc. Cheers, Vincenzo Il giorno ven 8 set 2023 alle ore 21:05 Mina Galić <free...@igalic.co> ha scritto: > Hi folks, > > for the past two or so weeks, I've been trying to document the > virtio functions: You can see some of my progress here: > > https://codeberg.org/meena/freebsd-src/commits/branch/improve/virtio > > I'm currently trying to document virtio_alloc_virtqueues. > The second argument, flags, is only ever called with 0, and > never passed on to anything. So I thought I'd remove it. > However, there *is* this comment in if_vtnet.c: > > /* > * TODO: Enable interrupt binding if this is multiqueue. This will > * only matter when per-virtqueue MSIX is available. > */ > if (sc->vtnet_flags & VTNET_FLAG_MQ) > flags |= 0; > > > after which flags are still set to 0. for now?? > What does this mean? > > Kind regards, > > Mina Galić > >
