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From: "David S. Miller" <davem@redhat.com>
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Date: Tue, 3 Jul 2001 00:18:58 -0700 (PDT)
To: mdaljeet@in.ibm.com
Cc: linux-kernel@vger.kernel.org
Subject: Re: virt_to_bus and virt_to_phys on Apple G4 target
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mdaljeet@in.ibm.com 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
details.

Later,
David S. Miller
davem@redhat.com
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