virtio — archive

[Michael S. Tsirkin <pbonzini@redhat.com>]

On Fri, Aug 17, 2018 at 07:04:42PM +0200, Paolo Bonzini wrote: > Define them in terms of descriptors, not segments, and explain what the > driver and device are to use them for. > > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> > --- > content.tex 17 +++++++++++++---- > 1 file changed, 13 insertions(+), 4 deletions(-) > > diff --git a/content.tex b/content.tex > index 4cdfeef..fd3a3c2 100644 > --- a/content.tex > +++ b/content.tex > @@ -3515,11 +3515,11 @@ device except where noted. > subsection{Feature bits}label{sec:Device Types / Block Device / Feature bits} > > egin{description} > -item[VIRTIO_BLK_F_SIZE_MAX (1)] Maximum size of any single segment is > - in field{size_max}. > +item[VIRTIO_BLK_F_SIZE_MAX (1)] Maximum size of any single descriptor in > + the data portion of a request ("segment") is in field{size_max}. > > -item[VIRTIO_BLK_F_SEG_MAX (2)] Maximum number of segments in a > - request is in field{seg_max}. > +item[VIRTIO_BLK_F_SEG_MAX (2)] Maximum number of descriptors in the > + data portion of a request ("segments") is in field{seg_max}. > > item[VIRTIO_BLK_F_GEOMETRY (4)] Disk-style geometry specified in > field{geometry}. > @@ -3762,6 +3762,10 @@ error or VIRTIO_BLK_S_UNSUPP for a request unsupported by device: > A driver SHOULD NOT submit a request which would cause a read or write > beyond field{capacity}. > > +A driver SHOULD NOT submit a request which has more than field{seg_max} > +descriptors in the data portion, or which has more than field{size_max} > +bytes in a single descriptor in the data portion. > + > A driver SHOULD accept the VIRTIO_BLK_F_RO feature if offered. > > A driver MUST set field{sector} to 0 for a VIRTIO_BLK_T_FLUSH request. > @@ -3782,6 +3786,11 @@ a range of sectors has been discarded. > A device MUST set the field{status} byte to VIRTIO_BLK_S_IOERR for a > request which would cause a read or write beyond field{capacity}. > > +A device MAY set the field{status} byte to VIRTIO_BLK_S_IOERR for a > +request Well device can always do this for any request, right? I think the distinction is that it can do this for all such requests? > which has more than field{seg_max} descriptors in the data > +portion, or which has more than field{size_max} bytes in a single > +descriptor in the data portion. > + Since it's SHOULD NOT for driver, I think another assumption is that device must handle such huge requests anyway then? Do all host implementations actually satisfy this requirement? > A device MUST set the field{status} byte to VIRTIO_BLK_S_IOERR > for a write request if the VIRTIO_BLK_F_RO feature if offered, and MUST NOT > write any data. > -- > 2.17.1 > > > > --------------------------------------------------------------------- > To unsubscribe from this mail list, you must leave the OASIS TC that > generates this mail. Follow this link to all your TCs in OASIS at: > https://www.oasis-open.org/apps/org/workgroup/portal/my_workgroups.php