From: "David S. Miller" <davem@redhat.com>
To: Kanoj Sarcar <kanoj@google.engr.sgi.com>
Cc: Grant Grundler <grundler@cup.hp.com>, linux-mm@kvack.org
Subject: Re: IOMMU setup vs DAC (PCI)
Date: Fri, 9 Feb 2001 11:52:43 -0800 (PST) [thread overview]
Message-ID: <14980.19083.144384.865666@pizda.ninka.net> (raw)
In-Reply-To: <200102091947.LAA66193@google.engr.sgi.com>
Kanoj Sarcar writes:
> dma_addr_t should be unsigned long, which is 64 bits on 64 bit
> architectures, so things are fine there.
>
> On regular x86, dma_addr_t is u32, which still works.
It's 32-bit on sparc64 since 32-bit DMA addresses are all
we need since the IOMMU is used for anything.
In fact, if your architecture is doing nothing other
than PCI, you _OUGHT_ to make it 32-bit even on 64-bit
platforms because the PCI dma interface does not support
64-bit DACs in any way shape or form until 2.5.x in then
a new dma64_addr_t type will be used to denote a DAC
address.
Later,
David S. Miller
davem@redhat.com
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next prev parent reply other threads:[~2001-02-09 19:52 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-02-09 19:39 Grant Grundler
2001-02-09 19:42 ` David S. Miller
2001-02-09 20:04 ` Grant Grundler
2001-02-09 19:47 ` Kanoj Sarcar
2001-02-09 19:52 ` David S. Miller [this message]
2001-02-09 20:07 ` Kanoj Sarcar
2001-02-09 20:23 ` David S. Miller
2001-02-09 21:11 ` Kanoj Sarcar
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