I/O Interfaces & Buses
Which correctly lists the three protocols that make up CXL?
- ACXL.usb, CXL.sata and CXL.hdmi
- BCXL.read, CXL.write and CXL.erase
- CCXL.io (PCI Express-equivalent I/O), CXL.cache (device caches CPU memory) and CXL.mem (CPU uses device memory)
Show answer and explanation
Answer: C. CXL.io (PCI Express-equivalent I/O), CXL.cache (device caches CPU memory) and CXL.mem (CPU uses device memory)
CXL.io is essentially PCI Express traffic used for device discovery, configuration, interrupts and so on. CXL.cache lets an accelerator cache CPU-side memory in its own cache while keeping coherence. CXL.mem lets the CPU read and write device memory like ordinary memory. A memory-expansion device uses CXL.io and CXL.mem, while an accelerator may use all three.
- A. These are names of other external interfaces.
- B. These sound like flash operations, not CXL protocols.
- C. Correct. They are combined according to the use case.