I/O Interfaces & Buses

Which describes CXL (Compute Express Link)?

  1. AA standard for connecting chiplets inside a package
  2. BA standard that uses the PCI Express physical layer to allow coherent memory sharing between CPUs and accelerators or memory devices
  3. CA new wireless LAN standard
Show answer and explanation

Answer: B. A standard that uses the PCI Express physical layer to allow coherent memory sharing between CPUs and accelerators or memory devices

With PCI Express, coherence between device memory and CPU caches is not maintained by hardware, so software had to take care of it. CXL runs on the same physical layer as PCI Express and adds protocols that maintain cache coherence and let the CPU read and write device memory like ordinary memory. It is used for sharing data with accelerators and for expanding memory.

  • A. That is UCIe or similar.
  • B. Correct. It uses the same connectors as PCI Express.
  • C. It has nothing to do with wireless LAN.
Practice this topic Back to topic

More I/O Interfaces & Buses questions

  1. What is an advantage of memory expansion using CXL (CXL memory)?
  2. Which correctly lists the three protocols that make up CXL?
  3. What is the role of equalizers (such as CTLE and DFE) in high-speed serial receivers?
  4. Which statement about the eye diagram used to assess high-speed serial signal quality is correct?
  5. Why does raising serial link speed make it harder to send signals over board traces of the same length, sometimes requiring retimers along the way?