Storage systems, AI infrastructure, and the occasional strong opinion.
For 40 years, the memory hierarchy was a clean staircase: registers, L1, L2, L3, DRAM, SSD, disk. CXL inserts a new step between DRAM and SSD. Pooled, shared, hardware-coherent memory at 150-400 nanoseconds. For storage systems, it means shared metadata without consensus and memory pools that eliminate stranded DRAM.
NVMe over Fabrics was supposed to make remote flash indistinguishable from local flash. Six years in, TCP added latency nobody budgeted for, RDMA requires a network engineering PhD, and half the industry is deploying NVMe-oF without understanding what they're buying.
The Linux kernel I/O stack was designed when a disk seek took 10 milliseconds. NVMe completes I/O in 10 microseconds. Two competing approaches emerged to fix this: SPDK rips out the kernel entirely, io_uring makes it fast enough. SPDK won the benchmarks. io_uring is winning the war.