Plumbing SDXI into Linux: From DMA Engine to User‑Space Offloads
summary
SDXI extends DMA engines to handle multiple address spaces and user‑space ownership via PASID/AKEY validation and 64‑byte descriptors with vendor extension slots. An upstream RFC wires SDXI into Linux as a DMA‑engine offload (pool mode only today; IQ completion and locking are pending) and a separate IOCTL UAPI plus user library targets full SDXI 1.0. The prototype performs in‑house inter‑VM memcopy, memset and folio page copies without hypervisor hops, and the patchset has been under review for about two months.
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