From: acmay@acmay.homeip.net
To: "David S. Miller" <davem@redhat.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: virt_to_bus and virt_to_phys on Apple G4 target
Date: Wed, 4 Jul 2001 15:03:42 -0700 [thread overview]
Message-ID: <20010704150342.C822@sink.san.rr.com> (raw)
In-Reply-To: <CA256A7E.0020F52C.00@d73mta01.au.ibm.com> <15169.29154.670946.785981@pizda.ninka.net>
In-Reply-To: <15169.29154.670946.785981@pizda.ninka.net>; from davem@redhat.com on Tue, Jul 03, 2001 at 12:18:58AM -0700
On Tue, Jul 03, 2001 at 12:18:58AM -0700, David S. Miller wrote:
>
> 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.
What about non-PCI devices? The IBM 405GP on-chip ethernet controller
is not PCI. It isn't in the standard kernel yet, but I am sure there
are other things that do DMA that aren't PCI.
next prev parent reply other threads:[~2001-07-04 22:04 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-07-03 5:57 virt_to_bus and virt_to_phys on Apple G4 target mdaljeet
2001-07-03 7:18 ` David S. Miller
2001-07-04 22:03 ` acmay [this message]
2001-07-04 7:56 ` Paul Mackerras
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