Paper Title: QEMU-based Emulator in a Proof-of-Concept CXL SSD Ecosystem

Paper Abstract: CXL interface goes beyond the DIMM slots to augment the system memory bandwidth and capacity. To aid software ecosystem development efforts before the CXL supported devices start arriving, the QEMU community has added emulated CXL type 3 memory expansion device, and support for such devices in Linux. At Samsung, we see the potential of CXL to aid the seamless merger of memory and storage and built a Proof-of-Concept NAND flash-based CXL SSD, one that shows up to the OS as an NVMe device via CXL.io protocol and is also enabled for load/store access using the CXL.mem protocol when memory-mapped. Software changes are needed to adapt their access methods according to their expected access patterns. This talk will describe how we extended and merged the existing NVMe virtual device and the CXL type 3 emulated device in QEMU into a dual-mode CXL SSD device attached to the CXL bus. CXL SSD-aware drivers register the device for dual-mode, and file system changes enable direct access to the files when memory-mapped. Also included will be a discussion of the status of upstreaming efforts that have been completed at the time of this talk.

Paper Author: Tong Zhang, Sr Research Engineer, Samsung Semiconductor

Author Bio: Dr. Tong Zhang is a Sr Research Engineer in the Systems Technology Group, Samsung Memory Solution Lab (https://samsungmsl.com/) in San Jose, California. His interest spans programming language, operating system, storage system and new memory technology, and also contributes to open source projects like Linux kernel, FreeBSD and LLVM. He has a doctoral degree in computer science from Virginia Tech.