You can read PORTING in the root of the tree.
It would be best if you'd explain your goal first, instead of doing a
deep dive into implementation details.
On Fri, May 04, 2012 at 09:20:38AM +0800, YIMIN CHEN wrote:
> Hi Ben,
>
> Thank you for the detailed information! I read this part of the code,
> and have some confusion. Can you please review the following to see if
> my understanding of code is correct?
>
> 1) ofproto/ code is userspace code, and datapath/ code is the actual dp code.
> 2) ofproto handles the rule insertion from control plane, and datapath
> handles the actual flow lookup.
> 3) resubmit is handled in userspace? I saw the resubmit logic
> xlate_nicira_action() is in ofproto I didn't see find any code in
> datapath that handles resubmit, not even in ovs-ofctl.c. Is
> xlate_nicira_action() doing flow insertion with resubmit action or
> actually performing the dp actions? I am confused.
>
> What is the relationship between ofproto userspace and the dp code?
> what is the difference between xlate table action and odp action?
>
> I think I am very confused, if there is any documentation I can read
> to understand this design better, would you please give me a pointer?
>
> Thanks!
> Yimin
>
> On Thu, May 3, 2012 at 11:30 AM, Ben Pfaff <b...@nicira.com> wrote:
> > It's documented in nicira-ext.h:
> >
> > /* Action structures for NXAST_RESUBMIT and NXAST_RESUBMIT_TABLE.
> > *
> > * These actions search one of the switch's flow tables:
> > *
> > * - For NXAST_RESUBMIT_TABLE only, if the 'table' member is not 255,
> > then
> > * it specifies the table to search.
> > *
> > * - Otherwise (for NXAST_RESUBMIT_TABLE with a 'table' of 255, or for
> > * NXAST_RESUBMIT regardless of 'table'), it searches the current flow
> > * table, that is, the OpenFlow flow table that contains the flow from
> > * which this action was obtained. If this action did not come from a
> > * flow table (e.g. it came from an OFPT_PACKET_OUT message), then
> > table 0
> > * is the current table.
> > *
> > * The flow table lookup uses a flow that may be slightly modified from the
> > * original lookup:
> > *
> > * - For NXAST_RESUBMIT, the 'in_port' member of struct
> > nx_action_resubmit
> > * is used as the flow's in_port.
> > *
> > * - For NXAST_RESUBMIT_TABLE, if the 'in_port' member is not
> > OFPP_IN_PORT,
> > * then its value is used as the flow's in_port. Otherwise, the
> > original
> > * in_port is used.
> > *
> > * - If actions that modify the flow (e.g. OFPAT_SET_VLAN_VID) precede
> > the
> > * resubmit action, then the flow is updated with the new values.
> > *
> > * Following the lookup, the original in_port is restored.
> > *
> > * If the modified flow matched in the flow table, then the corresponding
> > * actions are executed. Afterward, actions following the resubmit in the
> > * original set of actions, if any, are executed; any changes made to the
> > * packet (e.g. changes to VLAN) by secondary actions persist when those
> > * actions are executed, although the original in_port is restored.
> > *
> > * Resubmit actions may be used any number of times within a set of actions.
> > *
> > * Resubmit actions may nest to an implementation-defined depth. Beyond
> > this
> > * implementation-defined depth, further resubmit actions are simply
> > ignored.
> > *
> > * NXAST_RESUBMIT ignores 'table' and 'pad'. NXAST_RESUBMIT_TABLE requires
> > * 'pad' to be all-bits-zero.
> > *
> > * Open vSwitch 1.0.1 and earlier did not support recursion. Open vSwitch
> > * before 1.2.90 did not support NXAST_RESUBMIT_TABLE.
> > */
> > struct nx_action_resubmit {
> > ovs_be16 type; /* OFPAT_VENDOR. */
> > ovs_be16 len; /* Length is 16. */
> > ovs_be32 vendor; /* NX_VENDOR_ID. */
> > ovs_be16 subtype; /* NXAST_RESUBMIT. */
> > ovs_be16 in_port; /* New in_port for checking flow table.
> > */
> > uint8_t table; /* NXAST_RESUBMIT_TABLE: table to use. */
> > uint8_t pad[3];
> > };
> > OFP_ASSERT(sizeof(struct nx_action_resubmit) == 16);
> >
> > and in ovs-ofctl(8):
> >
> > resubmit:port
> > resubmit([port],[table])
> > Re-searches this OpenFlow flow table (or the table
> > whose
> > number is specified by table) with the in_port
> > field
> > replaced by port (if port is specified) and executes
> > the
> > actions found, if any, in addition to any other
> > actions
> > in this flow entry.
> >
> > Recursive resubmit actions are obeyed up to an
> > implemen‐
> > tation-defined maximum depth. Open vSwitch 1.0.1
> > and
> > earlier did not support recursion; Open vSwitch
> > before
> > 1.2.90 did not support table.
> >
> >
> > On Thu, May 03, 2012 at 09:54:08AM +0800, YIMIN CHEN wrote:
> >> Hi Ben,
> >>
> >> Thank you for your reply! I saw there is some code about resubmit
> >> Nicira extension action, but that seems to be in userspace ofproto.c,
> >> not in datapath, so I didn't know that is related. Could you help
> >> clarify for me how does resubmit work?
> >>
> >>
> >> Thanks!
> >> Yimin
> >>
> >> On Wed, May 2, 2012 at 12:40 PM, Ben Pfaff <b...@nicira.com> wrote:
> >> > On Wed, May 02, 2012 at 10:53:10AM +0800, YIMIN CHEN wrote:
> >> >> I am looking at ovs dp code, and is looking at a correct way for a
> >> >> flow to traverse the table twice. The goal is like this:
> >> >>
> >> >> flow lookup => tbl_lookup()
> >> >> perform actions => execute_actions() which changes the packet
> >> >> flow lookup using the new packet => tbl_lookup()
> >> >> perform actions on the new packet => execute_actions.
> >> >
> >> > Do you want the "resubmit" Nicira extension action?
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