DPDK Backend: PNA Pass metadata support #3245
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| @@ -69,5 +69,17 @@ class DirectionToRegRead : public Transform { | |||
| replaceDirectionWithRegRead(IR::IndexedVector<IR::DpdkAsmStatement> stmts); | |||
| }; | |||
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| class PrependPassRecircId : public Transform { | |||
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The comment that accompanies this PR should be present in the code too, here.
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I am not familiar with PNA, can you also explain how this recirc works?
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The recirculate() extern corresponds to "recirculate" instruction and marks the packet for recirculation. This means that when packet reaches tx instruction, it is reinjected into the pipeline for another full pass instead of being sent to the output port.
The same packet can be recirculated multiple times, with the recirculation pass number retrieved by the "recircid" instruction which corresponds to "pass" metadata. The pass number can be used by the program to execute different code on the same packet in different pipeline passes. The packet meta-data is preserved between the pipeline passes.
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DPDK reference patch for packet recirculation
https://patches.dpdk.org/project/dpdk/patch/[email protected]/
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There is no "recirculate" extern in your P4 examples. |
Updated the examples. |
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@mbudiu-vmw Can this PR be merged?. |
DPDK implements pass metadata using "recircid" instruction.
All occurrences of pass metadata usage should be prepended with recircid instruction to fetch the latest pass_id from the target.
"recircid" instruction takes a metadata type as argument to fetch the pass_id into that metadata.