> > +static void virtio_pmem_flush(VirtIODevice *vdev, VirtQueue *vq) > > +{ > > + VirtQueueElement *elem; > > + VirtIOPMEM *pmem = VIRTIO_PMEM(vdev); > > + HostMemoryBackend *backend = MEMORY_BACKEND(pmem->memdev); > > + int fd = memory_region_get_fd(&backend->mr); > > + > > + elem = virtqueue_pop(vq, sizeof(VirtQueueElement)); > > + if (!elem) { > > + return; > > + } > > + /* flush raw backing image */ > > + fsync(fd); > > fsync(2) is a blocking syscall. This can hang QEMU for an unbounded > amount of time. o.k. Main thread will block, agree. > > Please do the fsync from a thread pool. See block/file-posix.c's > aio_worker() for an example. Sure! > > > +static void virtio_pmem_get_config(VirtIODevice *vdev, uint8_t *config) > > +{ > > + VirtIOPMEM *pmem = VIRTIO_PMEM(vdev); > > + struct virtio_pmem_config *pmemcfg = (struct virtio_pmem_config *) > > config; > > + > > + pmemcfg->start = pmem->start; > > + pmemcfg->size = pmem->size; > > Endianness. Please use virtio_st*_p() instead. sure. > > > +#define VIRTIO_PMEM_PLUG 0 > > What is this? will remove Thanks, Pankaj