Messages in this thread | | | Date | Tue, 30 Mar 1999 08:35:01 -0500 | From | Brian Gerst <> | Subject | Re: Address spaces on a i386 - Getting Confused |
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Paul Sargent wrote: > As far as I can see there are probably three distinct address spaces used > (please correct me if I'm wrong) > * Kernel space Virtual Addresses > * User Space Virtual Addresses (1 address space per process) > * Physical (Bus) addresses
Actually physical and bus addresses are not always identical. On the i386 they are the same but on some other achitectures they are not. So you also need phys_to_bus() (which is just an empty macro on the i386) to return the real bus address which you can give to the card's DMA controller.
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Brian Gerst
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