From: David Mosberger <davidm@napali.hpl.hp.com>
To: Dave Olien <dmo@osdl.org>
Cc: "David S. Miller" <davem@redhat.com>,
phillips@arcor.de, davidm@hpl.hp.com, davidm@napali.hpl.hp.com,
axboe@suse.de, _deepfire@mail.ru, linux-kernel@vger.kernel.org
Subject: Re: DAC960 in 2.5.38, with new changes
Date: Tue, 24 Sep 2002 10:11:26 -0700 [thread overview]
Message-ID: <15760.40126.378814.639307@napali.hpl.hp.com> (raw)
In-Reply-To: <20020924095456.A17658@acpi.pdx.osdl.net>
>>>>> On Tue, 24 Sep 2002 09:54:56 -0700, Dave Olien <dmo@osdl.org> said:
Dave> According to the Documentation/DMA-mapping.txt file, the new
Dave> DMA mapping interfaces should allow all PCI transfers to use
Dave> 32-bit DMA addresses. Controllers on the PCI bus should never
Dave> need to use DAC PCI transfers. Based on this, writel() should
Dave> work even on ia64.
Warning: there is a big difference between *can* and *want*. On ia64
machines with an Intel chipset, the PCI DMA interface is implemented
via bounce buffers, so it will be *much* slower than DAC. For this
reason, it is preferable on ia64 to use DAC where possible (and just
in case Dave Miller starts asking about this: yes, the hp zx1 chipset
for Itanium 2 does have a hardware I/O TLB... ;-).
--david
next prev parent reply other threads:[~2002-09-24 17:06 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-09-23 19:04 DAC960 in 2.5.38, with new changes Dave Olien
2002-09-23 19:19 ` David Mosberger
2002-09-23 20:40 ` David S. Miller
2002-09-23 20:53 ` David Mosberger
2002-09-23 20:57 ` David S. Miller
2002-09-23 21:24 ` David Mosberger
2002-09-23 21:17 ` David S. Miller
2002-09-23 21:32 ` David Mosberger
2002-09-23 21:28 ` David S. Miller
2002-09-23 21:31 ` Daniel Phillips
2002-09-23 21:33 ` David Mosberger
2002-09-23 21:28 ` David S. Miller
2002-09-23 21:40 ` Daniel Phillips
2002-09-23 21:45 ` David Mosberger
2002-09-23 20:44 ` Daniel Phillips
2002-09-23 20:54 ` David S. Miller
2002-09-24 16:54 ` Dave Olien
2002-09-24 17:11 ` David Mosberger [this message]
2002-09-24 17:28 ` Dave Olien
2002-09-24 18:21 ` David Mosberger
2002-09-24 18:25 ` Dave Olien
2002-09-24 19:12 ` David Mosberger
2002-09-24 18:45 ` Dave Olien
2002-09-24 17:50 ` Daniel Phillips
2002-09-24 18:27 ` David Mosberger
2002-09-24 17:39 ` Daniel Phillips
2002-09-25 22:20 ` DAC960, documentation links Daniel Phillips
2002-09-25 22:23 ` Daniel Phillips
2002-09-26 0:02 ` Mr. James W. Laferriere
2002-09-26 16:13 ` DAC960 in 2.5.38, with new changes Alan Cox
2002-09-24 17:45 ` Daniel Phillips
2002-09-25 21:42 ` davide.rossetti
2002-09-23 20:39 ` Daniel Phillips
2002-09-23 21:41 ` Dave Olien
2002-09-23 21:53 ` Daniel Phillips
2002-09-23 22:03 ` Dave Olien
2002-09-23 22:22 ` Daniel Phillips
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