[RFC PATCH 0/2] per-device DMA properties, with igb as the first user

[Md Rayhanul Islam <r97yhan@gmail.com>]

This RFC reworks the BCM2711 DMA fix around a per-device DMA context and
an EAL sync API, after the feedback on the first posting [1].

On Raspberry Pi 4 / Compute Module 4 the PCIe host bridge translates DMA
addresses and is not cache coherent, so a device such as the Intel I210
cannot DMA at all without both being handled.

What changed since the first posting:

* The translation and the coherency are read per device from its own
  bridge, not kept as one process-wide offset.  EAL no longer rewrites
  IOVAs; the driver translates where it programs the hardware.
* A driver opts in with RTE_PCI_DRV_DMA_NONCOHERENT, and the bus refuses
  such a device to any driver that has not.  That replaces the refusal
  written into em by hand.
* The cache maintenance is an experimental EAL interface with explicit
  directions, and the loops end in DSB SY.
* Completion comes from the Done bits, not the head register.
* Both environment variables are gone.

Tested between two Compute Module 4 boards with Intel I210s, both running
this series: testpmd txonly holds 1.42 Mpps with 64-byte frames, and a
512 MB UDP transfer with DPDK at both ends arrives byte-identical.  Built
with GCC and with clang 14 -Werror.

[1] https://inbox.dpdk.org/dev/20260918225045.177125-1-r97yhan@gmail.com/

Md Rayhanul Islam (2):
  eal/pci: add per-device DMA translation and synchronization
  net/e1000: support non-coherent DMA

 .mailmap                               |   1 +
 doc/guides/rel_notes/release_26_11.rst |  20 ++
 drivers/bus/pci/bus_pci_driver.h       |   2 +
 drivers/bus/pci/linux/pci.c            |   6 +
 drivers/bus/pci/linux/pci_dma_ranges.c | 168 ++++++++++
 drivers/bus/pci/linux/pci_init.h       |   2 +
 drivers/bus/pci/meson.build            |   1 +
 drivers/bus/pci/pci_common.c           |  17 +
 drivers/bus/pci/private.h              |   2 +
 drivers/bus/pci/rte_bus_pci.h          |  52 ++++
 drivers/net/intel/e1000/e1000_ethdev.h |  19 ++
 drivers/net/intel/e1000/igb_ethdev.c   |   9 +-
 drivers/net/intel/e1000/igb_rxtx.c     | 409 +++++++++++++++++++++++--
 lib/eal/include/meson.build            |   1 +
 lib/eal/include/rte_mem_sync.h         | 133 ++++++++
 15 files changed, 815 insertions(+), 27 deletions(-)
 create mode 100644 drivers/bus/pci/linux/pci_dma_ranges.c
 create mode 100644 lib/eal/include/rte_mem_sync.h

-- 
2.34.1