Re: virt_to_bus and virt_to_phys on Apple G4 target

From: David S. Miller (
Date: Tue Jul 03 2001 - 02:18:58 EST 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
> 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?
> 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?

virt_to_bus() and bus_to_virt() are deprecated interfaces and should
not be used by anything new. See Documentation/DMA-mapping.txt for

David S. Miller
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