CMA&DMA
Reserved-memory 参考：http://www.wowotech.net/memory_management/cma.html https://xilinx-wiki.atlassian.net/wiki/spaces/A/pages/18841683/Linux+Reserved+Memory?view=blog /Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt 定义了 no-map 属性的，不会自动映射到虚拟地址，需要自行在 driver 中映射。 // dts reserved: buffer@0x38000000 { no-map; reg = <0x38000000 0x08000000>; }; /* Get reserved memory region from Device-tree */ np = of_parse_phandle(dev->of_node, "memory-region", 0); rc = of_address_to_resource(np, 0, &r); lp->paddr = r.start; lp->vaddr = memremap(r.start, resource_size(&r), MEMREMAP_WB); 定义"shared-dma-pool" 就可以创建 DMA memory pool，使用 DMA engine API 了。of_reserved_mem_device_init 中会帮我们创建映射。（DMA 在 of_reserved_mem_device_init 阶段会进行 memremap 同上，这个 remap 不是直接映射的方式）。 // dts reserved: buffer@0 { compatible = "shared-dma-pool"; no-map; reg = <0x0 0x70000000 0x0 0x10000000>; }; /* Initialize reserved memory resources */ rc = of_reserved_mem_device_init(dev); /* Allocate memory */ dma_set_coherent_mask(dev, 0xFFFFFFFF); lp->vaddr = dma_alloc_coherent(dev, ALLOC_SIZE, &lp->paddr, GFP_KERNEL); log:...