On Tue, Jul 28, 2020 at 12:52:11PM +0200, Marc Hartmayer wrote: > On Tue, Jul 21, 2020 at 06:44 PM +0200, Halil Pasic <[email protected]> > wrote: > > On Tue, 21 Jul 2020 09:40:10 -0400 > > "Michael S. Tsirkin" <[email protected]> wrote: > > > >> On Fri, Jul 17, 2020 at 11:29:28AM +0200, Marc Hartmayer wrote: > >> > Since virtio existed even before it got standardized, the virtio > >> > standard defines the following types of virtio devices: > >> > > >> > + legacy device (pre-virtio 1.0) > >> > + non-legacy or VIRTIO 1.0 device > >> > + transitional device (which can act both as legacy and non-legacy) > >> > > >> > Virtio 1.0 defines the fields of the virtqueues as little endian, > >> > while legacy uses guest's native endian [1]. Currently libvhost-user > >> > does not handle virtio endianness at all, i.e. it works only if the > >> > native endianness matches with whatever is actually needed. That means > >> > things break spectacularly on big-endian targets. Let us handle virtio > >> > endianness for non-legacy as required by the virtio specification > >> > [1]. We will fence non-legacy virtio devices with the upcoming patch. > >> > > >> > [1] > >> > https://docs.oasis-open.org/virtio/virtio/v1.1/cs01/virtio-v1.1-cs01.html#x1-210003 > >> > > >> > Signed-off-by: Marc Hartmayer <[email protected]> > >> > > >> > --- > >> > Note: As we don't support legacy virtio devices > >> > >> Who's "we" in this sentence? vhost user supports legacy generally ... > > > > In that sentence "we" is the library "libvhost-user". I would like > > to avoid s390x being an oddball regarding this. Marc's previous > > version made an attempt at correct endianness handling for legacy > > and non-legacy. That spawned a discussion on how we don't want > > legacy devices in this context. This series makes what seemed to be the > > consensus reached in that discussion explicit: namely that libvhost-user > > does not support legacy-virtio. > > Hi Michael, > > Polite ping - what’s your opinion? Thanks in advance. > > […snip]
It's a reasonable limitation, but I also don't see anything that verifies that device is modern only. E.g. fail setting features if VIRTIO_F_VERSION_1 is not there? > -- > Kind regards / Beste Grüße > Marc Hartmayer > > IBM Deutschland Research & Development GmbH > Vorsitzender des Aufsichtsrats: Gregor Pillen > Geschäftsführung: Dirk Wittkopp > Sitz der Gesellschaft: Böblingen > Registergericht: Amtsgericht Stuttgart, HRB 243294
