[PATCH RFC 00/13] dmaengine: Smart Data Accelerator Interface (SDXI) basic support

Nathan Lynch via B4 Relay
2025-09-05T18:48:50Z

The Smart Data Accelerator Interface (SDXI) is a vendor-neutral
architecture for memory-to-memory data movement offload designed for
kernel bypass and virtualization.

General information on SDXI may be found at:
https://www.snia.org/sdxi

This submission adds a driver with basic support for PCIe-hosted SDXI 1.0
implementations and includes a DMA engine provider.

It is very much a work in progress. Among other issues, the DMA
provider code only supports single-threaded polled mode, and context
management should use better data structures.

While we're addressing those shortcomings, we'd appreciate any
feedback on:

* Where the code should live. SDXI entails a fair amount of code for
context and descriptor management, and we expect to eventually add a
character device ABI for user space access. Should all of this go in
drivers/dma/sdxi?

* Whether the DMA engine provider should use virt-dma/vchan. SDXI
submission queues can be almost arbitrarily large, and I'm not sure
putting a software queue in front of that makes sense.

Planned future SDXI work (out of scope for this series):

* Character device for user space access. We are evaluating the uacce
framework for this.

* Support for operation types to be added in future SDXI revisions.

* Greater configurability for control structures, e.g. descriptor ring
size.

The latest released version of the SDXI specification is 1.0:
https://www.snia.org/sites/default/files/technical-work/sdxi/release/SNIA-SDXI-Specification-v1.0a.pdf

Draft versions of future SDXI specifications in development may be found at:
https://www.snia.org/tech_activities/publicreview#sdxi

---
Nathan Lynch (13):
PCI: Add SNIA SDXI accelerator sub-class
dmaengine: sdxi: Add control structure definitions
dmaengine: sdxi: Add descriptor encoding and unit tests
dmaengine: sdxi: Add MMIO register definitions
dmaengine: sdxi: Add software data structures
dmaengine: sdxi: Add error reporting support
dmaengine: sdxi: Import descriptor enqueue code from spec
dmaengine: sdxi: Context creation/removal, descriptor submission
dmaengine: sdxi: Add core device management code
dmaengine: sdxi: Add PCI driver support
dmaengine: sdxi: Add DMA engine provider
dmaengine: sdxi: Add Kconfig and Makefile
MAINTAINERS: Add entry for SDXI driver

MAINTAINERS | 7 +
drivers/dma/Kconfig | 2 +
drivers/dma/Makefile | 1 +
drivers/dma/sdxi/.kunitconfig | 4 +
drivers/dma/sdxi/Kconfig | 23 ++
drivers/dma/sdxi/Makefile | 17 ++
drivers/dma/sdxi/context.c | 547 ++++++++++++++++++++++++++++++++++++
drivers/dma/sdxi/context.h | 28 ++
drivers/dma/sdxi/descriptor.c | 197 +++++++++++++
drivers/dma/sdxi/descriptor.h | 107 +++++++
drivers/dma/sdxi/descriptor_kunit.c | 181 ++++++++++++
drivers/dma/sdxi/device.c | 401 ++++++++++++++++++++++++++
drivers/dma/sdxi/dma.c | 409 +++++++++++++++++++++++++++
drivers/dma/sdxi/dma.h | 12 +
drivers/dma/sdxi/enqueue.c | 136 +++++++++
drivers/dma/sdxi/enqueue.h | 16 ++
drivers/dma/sdxi/error.c | 340 ++++++++++++++++++++++
drivers/dma/sdxi/error.h | 16 ++
drivers/dma/sdxi/hw.h | 249 ++++++++++++++++
drivers/dma/sdxi/mmio.h | 92 ++++++
drivers/dma/sdxi/pci.c | 216 ++++++++++++++
drivers/dma/sdxi/sdxi.h | 206 ++++++++++++++
include/linux/pci_ids.h | 1 +
23 files changed, 3208 insertions(+)
---
base-commit: c17b750b3ad9f45f2b6f7e6f7f4679844244f0b9
change-id: 20250813-sdxi-base-73d7c9fdce57

Best regards,
--
Nathan Lynch <nathan.lynch@amd.com>