P4TC hits a brick wall

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2024-07-07 12:00:04

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By Jonathan Corbet June 10, 2024 P4, short for "Programming Protocol-independent Packet Processors", is a programming language aimed at networking devices; it is useful for the configuration of firewalls and complicated routing architectures. Since a lot of advanced networking is done with Linux systems, it stands to reason that there would be value in supporting P4 and, indeed, an implementation of P4 in the kernel's traffic-control subsystem was first posted by Jamal Hadi Salim at the beginning of 2023. After nearly 18 months, though, this feature has not been merged, and the chances of that happening would appear to be getting worse.

The kernel supports a number of traffic-control mechanisms in its networking subsystem; tc-flower is perhaps one of the most commonly used. The P4TC subsystem proposed by Salim fits into that subsystem, adding the ability to use the P4 language for the description of networking policies. It is entirely implemented in software, and runs within the kernel.