On Tue, 2016-01-12 at 09:58 +0000, Paul Durrant wrote: > My previous patch 03809ae7 "document transmit and receive wire formats > separately" improved documentation of the receive and transmit wire > formats but further clarifications were requested. > > This patch adds those clarifications. > > Signed-off-by: Paul Durrant <paul.durr...@citrix.com>
Acked-by: Ian Campbell <ian.campb...@citrix.com> > Cc: Ian Jackson <ian.jack...@eu.citrix.com> > Cc: Jan Beulich <jbeul...@suse.com> > Cc: Keir Fraser <k...@xen.org> > Cc: Tim Deegan <t...@xen.org> > --- > > v6: > - v4 of the original patch was committed so this is an > incremental version of the patch in v5. > > v5: > - Add extra clarifications. > --- > xen/include/public/io/netif.h | 28 ++++++++++++++++++++++++---- > 1 file changed, 24 insertions(+), 4 deletions(-) > > diff --git a/xen/include/public/io/netif.h > b/xen/include/public/io/netif.h > index 1790ea0..0a3272f 100644 > --- a/xen/include/public/io/netif.h > +++ b/xen/include/public/io/netif.h > @@ -154,19 +154,29 @@ > * Guest transmit > * ============== > * > - * This is the 'wire' format for packets: > + * This is the 'wire' format for transmit (frontend -> backend) packets: > + * > * Fragment 1: netif_tx_request_t - flags = NETTXF_* > * size = total packet size > * [Extra 1: netif_extra_info_t] - (only if fragment 1 flags include > * NETTXF_extra_info) > + * ... > * [Extra N: netif_extra_info_t] - (only if extra N-1 flags include > * XEN_NETIF_EXTRA_MORE) > * ... > * Fragment N: netif_tx_request_t - (only if fragment N-1 flags > include > - * NETTXF_more_data) > + * NETTXF_more_data - flags on > preceding > + * extras are not relevent here) > * flags = 0 > * size = fragment size > * > + * NOTE: > + * > + * This format slightly is different from that used for receive > + * (backend -> frontend) packets. Specifically, in a multi-fragment > + * packet the actual size of fragment 1 can only be determined by > + * subtracting the sizes of fragments 2..N from the total packet size. > + * > * Ring slot size is 12 octets, however not all request/response > * structs use the full size. > * > @@ -202,19 +212,29 @@ > * Guest receive > * ============= > * > - * This is the 'wire' format for packets: > + * This is the 'wire' format for receive (backend -> frontend) packets: > + * > * Fragment 1: netif_rx_request_t - flags = NETRXF_* > * size = fragment size > * [Extra 1: netif_extra_info_t] - (only if fragment 1 flags include > * NETRXF_extra_info) > + * ... > * [Extra N: netif_extra_info_t] - (only if extra N-1 flags include > * XEN_NETIF_EXTRA_MORE) > * ... > * Fragment N: netif_rx_request_t - (only if fragment N-1 flags > include > - * NETRXF_more_data) > + * NETRXF_more_data - flags on > preceding > + * extras are not relevent here) > * flags = 0 > * size = fragment size > * > + * NOTE: > + * > + * This format slightly is different from that used for transmit > + * (frontend -> backend) packets. Specifically, in a multi-fragment > + * packet the size of the packet can only be determined by summing the > + * sizes of fragments 1..N. > + * > * Ring slot size is 8 octets. > * > * rx request (netif_rx_request_t) _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
