10/03/2019 09:27, Shahaf Shuler: > The DPDK APIs expose 3 different modes to work with memory used for DMA: > > 1. Use the DPDK owned memory (backed by the DPDK provided hugepages). > This memory is allocated by the DPDK libraries, included in the DPDK > memory system (memseg lists) and automatically DMA mapped by the DPDK > layers. > > 2. Use memory allocated by the user and register to the DPDK memory > systems. Upon registration of memory, the DPDK layers will DMA map it > to all needed devices. After registration, allocation of this memory > will be done with rte_*malloc APIs. > > 3. Use memory allocated by the user and not registered to the DPDK memory > system. This is for users who wants to have tight control on this > memory (e.g. avoid the rte_malloc header). > The user should create a memory, register it through rte_extmem_register > API, and call DMA map function in order to register such memory to > the different devices. > > The scope of the patch focus on #3 above. > > Currently the only way to map external memory is through VFIO > (rte_vfio_dma_map). While VFIO is common, there are other vendors > which use different ways to map memory (e.g. Mellanox and NXP). > > The work in this patch moves the DMA mapping to vendor agnostic APIs. > Device level DMA map and unmap APIs were added. Implementation of those > APIs was done currently only for PCI devices. > > For PCI bus devices, the pci driver can expose its own map and unmap > functions to be used for the mapping. In case the driver doesn't provide > any, the memory will be mapped, if possible, to IOMMU through VFIO APIs. > > Application usage with those APIs is quite simple: > * allocate memory > * call rte_extmem_register on the memory chunk. > * take a device, and query its rte_device. > * call the device specific mapping function for this device. > > Future work will deprecate the rte_vfio_dma_map and rte_vfio_dma_unmap > APIs, leaving the rte device APIs as the preferred option for the user. > > Shahaf Shuler (6): > vfio: allow DMA map of memory for the default vfio fd > vfio: don't fail to DMA map if memory is already mapped > bus: introduce device level DMA memory mapping > net/mlx5: refactor external memory registration > net/mlx5: support PCI device DMA map and unmap > doc: deprecation notice for VFIO DMA map APIs
Applied, thanks
