Hi all, We want to design a PCI host embedded PowerPC board with a 3Go local RAM memory. This processor is a MPC74xx with an internal 32 bits and an external 36 bits address bus.
Usually, the mapping is : 0x00000000-0x80000000 : physical RAM 0x80000000-0xc0000000 : PCI memory access 0xc0000000-0xf0000000 : kernel virtual memory 0xf0000000-0xffffffff : IO area access 1) On this board, the physical memory will be : 0x00000000-0xc0000000 : physical RAM Where could we map PCI memory space ? 2) The kernel virtual memory usually has the same size as the physical RAM (two memory footprint for the same physical space ! ). The kernel virtual memory will be : 0xc0000000-0x180000000 : kernel virtual memory Where could we map IO space ? 3) Usually, all the host memory is mapped on pci bus. For a 32bits pci bus, we could not do this. Is it possible to only map on pci, the DMA memory area which is managed with the kmalloc(size, GFP_DMA) and kfree functions ? How can we set the DMA memory parameters (base address and size) ? Thanks for any idea Laurent
