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From: Grant Grundler <grundler@cup.hp.com>
To: linux-ia64@vger.kernel.org
Subject: Re: [Linux-ia64] BitKeeper tree for 2.4.x
Date: Thu, 17 Oct 2002 22:10:13 +0000	[thread overview]
Message-ID: <marc-linux-ia64-105590709805191@msgid-missing> (raw)
In-Reply-To: <marc-linux-ia64-105590709805154@msgid-missing>

Steffen Persvold wrote:
> Kinda complicated though... I thought the IO system didn't use coherence
> protocols, and it was because of that we needed API functions such as
> pci_dma_sync_single() and pci_dma_sync_sg() to manually ensure coherence..

The original problem was some IOMMU's can not support a static translation
for all physical memory - ie virt_to_bus() wouldn't work.
"manual coherence" works because the design accomodates SW IOTLB
("bounce buffers") model.

Supported HP PARISC and IA64 IOMMU's participate in the coherency protocol.

grant


  parent reply	other threads:[~2002-10-17 22:10 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2002-10-10 19:42 [Linux-ia64] BitKeeper tree for 2.4.x Bjorn Helgaas
2002-10-14 17:42 ` Bjorn Helgaas
2002-10-14 18:17 ` Steffen Persvold
2002-10-14 20:44 ` Grant Grundler
2002-10-17 16:46 ` Bjorn Helgaas
2002-10-17 18:16 ` Steffen Persvold
2002-10-17 18:31 ` Steffen Persvold
2002-10-17 19:38 ` Bjorn Helgaas
2002-10-17 21:53 ` Steffen Persvold
2002-10-17 22:10 ` Grant Grundler [this message]
2002-10-18  2:32 ` Steffen Persvold

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