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[multicast] wire up softnpu backend to multicast table ops#242

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zeeshanlakhani merged 3 commits intomulticast-e2efrom
zl/softnpu-with-mcast
Apr 28, 2026
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[multicast] wire up softnpu backend to multicast table ops#242
zeeshanlakhani merged 3 commits intomulticast-e2efrom
zl/softnpu-with-mcast

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@zeeshanlakhani zeeshanlakhani commented Mar 24, 2026

This wires up the softnpu ASIC backend to support multicast end-to-end by translating DPD's sidecar.p4 table operations into sidecar-lite.p4's simplified P4 pipeline.

AsicMulticastOps

We replace the stubbed AsicMulticastOps implementation (which returned "OperationUnsupported" for group creation and port addition with in-memory group tracking via McGroupData, following the tofino_stub pattern.

Group membership is used by the table translation layer to build port bitmaps for sidecar-lite's Replicate extern. Ports >= 128 are rejected at add time to match sidecar-lite's 128-bit bitmap width.

Table translation (asic/src/softnpu/table.rs)

We map sidecar.p4 table names to sidecar-lite equivalents and translate action parameters where the designs differ for emulation.

All multicast action arms are gated with #[cfg(feature = "multicast")].

References

@zeeshanlakhani zeeshanlakhani force-pushed the zl/softnpu-with-mcast branch from a3f94ef to abf35dd Compare March 30, 2026 05:54
@zeeshanlakhani zeeshanlakhani changed the title [multicast] Wire softnpu backend to multicast management protocol [multicast] wire up softnpu backend to multicast table ops Mar 30, 2026
@zeeshanlakhani zeeshanlakhani marked this pull request as ready for review March 30, 2026 06:30
@zeeshanlakhani zeeshanlakhani force-pushed the zl/softnpu-with-mcast branch from 594dd68 to abf35dd Compare April 1, 2026 03:09
@zeeshanlakhani zeeshanlakhani self-assigned this Apr 1, 2026
This wires up the softnpu ASIC backend to support multicast end-to-end by
translating DPD's sidecar.p4 table operations into sidecar-lite.p4's
simplified P4 pipeline.

## AsicMulticastOps

We replace the stubbed AsicMulticastOps implementation (which returned
"OperationUnsupported" for group creation and port addition with in-memory group
tracking via McGroupData, following the tofino_stub pattern.

Group membership is used by the table translation layer to build port
bitmaps for sidecar-lite's Replicate extern. Ports >= 128 are
rejected at add time to match sidecar-lite's 128-bit bitmap width.

## Table translation (asic/src/softnpu/table.rs)

We map sidecar.p4 table names to sidecar-lite equivalents and translate
action parameters where the designs differ for emulation.

All multicast action arms are gated with #[cfg(feature = "multicast")].

## References

- [softnpu #183](oxidecomputer/softnpu#183)
- [propolis #1093](oxidecomputer/propolis#1093)
- [p4rs #240](oxidecomputer/p4#240)
- [sidecar-lite #152](oxidecomputer/sidecar-lite#152)
- tokio: 1.50 (due to softnpu)
- oxide-tokio-rt: 0.1.3 (following-up from tokio's move to 1.50)
@zeeshanlakhani zeeshanlakhani force-pushed the zl/softnpu-with-mcast branch from abf35dd to b586dfd Compare April 1, 2026 03:24
@zeeshanlakhani zeeshanlakhani force-pushed the zl/softnpu-with-mcast branch 2 times, most recently from 3f64f2d to 8c60a82 Compare April 28, 2026 01:07
…ce list

`modify_group_external` wrote back `new.sources.or(existing)` to the
in-memory record while `update_external_tables` in the same call
canonicalized `new.sources` directly to rewrite the P4 source-filter
entries. A `None` update therefore cleared the P4 table but left a
stale `Some([...])` in memory.
@zeeshanlakhani zeeshanlakhani force-pushed the zl/softnpu-with-mcast branch from 8c60a82 to a8701ad Compare April 28, 2026 01:25
@zeeshanlakhani zeeshanlakhani merged commit e10e4f5 into multicast-e2e Apr 28, 2026
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@zeeshanlakhani zeeshanlakhani deleted the zl/softnpu-with-mcast branch April 28, 2026 02:46
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