[EMAIL PROTECTED] writes: > I am running linux 2.4.2 on Apple G4 machine. I think the 'PCI bus > addresses' and 'physical addresses' are same on this architecture. I They are the same on an Apple G4 but not necessarily on other PowerPC machines. It depends on the PCI host bridge implementation. > expected the two be different but according to asm/io.h 'virt_to_bus(addr) > = virt_to_phys(addr) + PCI_DRAM_OFFSET'. I printed the value of > 'PCI_DRAM_OFFSET' and that come out to be zero. Is this correct? Yes, for an Apple G4. > If I somehow get the physical address of a user space buffer in a module > and take this as a PCI bus address, will I be able to do DMA properly? Yes, on an Apple G4. If you use virt_to_bus then it should work on all PowerPC machines that I know of (that run 32-bit PPC/Linux). But as Dave points out, you should use the interfaces described in Documentation/DMA-mapping.txt instead if at all possible. It's quite possible that virt_to_bus will be removed during 2.5.x development. Paul. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
