On Thu, May 23, 2019 at 3:25 PM Johannes Berg <johannes@xxxxxxxxxxxxxxxx> wrote: > Not sure I understand why there's all this stuff about multiple FDs, > once you have access to the guest's memory, why do you still need a > second (or more) FDs? The memory regions could be different files (maybe additional RAM was hotplugged later). > Also, not sure I understand how the client is started? The vhost-user device backend can be launched before QEMU. QEMU is started with the UNIX domain socket path so it can connect. QEMU itself doesn't fork+exec the vhost-user device backend. It's expected that the user or the management stack has already launched the vhost-user device backend. > Once we have a connection, I guess as a client I'd at the very least > have to handle > * VHOST_USER_GET_FEATURES and reply with the features, obviously, which > is in this case just VHOST_USER_F_PROTOCOL_FEATURES? > > * VHOST_USER_SET_FEATURES - not sure, what would that do? the master > sends VHOST_USER_GET_PROTOCOL_FEATURES which is with this feature > bit? Especially since it says: "Slave that reported > VHOST_USER_F_PROTOCOL_FEATURES must support this message even before > VHOST_USER_SET_FEATURES was called." > > * VHOST_USER_GET_PROTOCOL_FEATURES - looking at the list, most I don't > really need here, but OK > > * VHOST_USER_SET_OWNER - ?? > > * VHOST_USER_RESET_OWNER - ignore > > * VHOST_USER_SET_MEM_TABLE - store the data/FDs for later use, I guess > > * VHOST_USER_SET_VRING_NUM - store the data for later use > * VHOST_USER_SET_VRING_ADDR - dito > * VHOST_USER_SET_VRING_BASE - dito > * VHOST_USER_SET_VRING_KICK - start epoll on the FD (assuming there is > one, give up if not?) - well, if ring is > enabled? > * VHOST_USER_SET_VRING_CALL - ... > > I guess there might be better documentation on the ioctl interfaces? > > > Do you know if there's a sample client/server somewhere? See contrib/libvhost-user in the QEMU source tree as well as the vhost-user-blk and vhost-user-scsi examples in the contrib/ directory. Stefan _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
