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/[email protected]/ 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
