On Fri, Jan 25, 2019 at 02:17:01PM -0500, Michael S. Tsirkin wrote: > On Fri, Jan 25, 2019 at 03:12:45PM +0000, Stefan Hajnoczi wrote: > > Based on the Linux guest driver code and the lack of more evidence in > > the spec, I'm pretty sure data[] doesn't need to be padded to 512 bytes > > for discard/write zero requests. > > OK. Must devices support such padding?
I see no reason to require padding. Host APIs and physical storage controllers do not require it. > > > Looking at the QEMU sources, it seems like it can deal with both and > > > always sets the status right behind the last byte: > > > > > > req->in = (void *)in_iov[in_num - 1].iov_base > > > + in_iov[in_num - 1].iov_len > > > - sizeof(struct virtio_blk_inhdr); > > > > > > Anyway, I think the virtio spec should be clearer here to avoid bad > > > implementations in the future, so maybe Changpeng or Michael could > > > update the spec here a little bit? > > > > Yep, good point. VIRTIO 1.1 is available for public comments, so I've > > CCed the list. > > > > Stefan > > Thanks! > Care creating a github issue? And maybe proposing a spec patch. Okay. I will do this on Wednesday 30th of January. Stefan
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