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A few months ago, I posted a piece about PLDA expanding its support for two emerging protocol standards: CXL™ and Gen-Z™. The Compute Express Link (CXL) specification defines a set of three protocols that run on top of the PCIe PHY layer. The current revision of the CXL (2.0) specification runs with the PCIe 5.0 PHY layer at a maximum link rate of 32GT/s per lane. There are a lot of parts to this specification and multiple implementation options, so a comprehensive support package will significantly help adoption. This is why PLDA brings flexible support for compute express link (CXL) to SoC and FPGA designers.

The Options

The three previously mentioned protocols that make up CXL are:

• CXL.io: which is very similar to traditional PCIe and is responsible for discovery, configuration, and all the other things that PCIe is responsible for
• CXL.cache: which gives CXL devices coherent, low latency access to shared host memory
• CXL.mem: which gives the host processor access to shared device memory

CXL defines 3 types of devices that leverage different combinations of these protocols depending on the use case.