From: Tim Wright <timw@splhi.com>
To: Matti Aarnio <matti.aarnio@zmailer.org>
Cc: Venkatesh Ramamurthy <Venkateshr@ami.com>,
"'Pavel Machek'" <pavel@suse.cz>,
adefacc@tin.it, linux-kernel@vger.kernel.org
Subject: Re: Confirmation request about new 2.4.x. kernel limits
Date: Tue, 9 Jan 2001 08:27:49 -0800 [thread overview]
Message-ID: <20010109082749.A2971@scutter.internal.splhi.com> (raw)
In-Reply-To: <1355693A51C0D211B55A00105ACCFE64E95137@ATL_MS1> <20010109142156.L25659@mea-ext.zmailer.org>
In-Reply-To: <20010109142156.L25659@mea-ext.zmailer.org>; from matti.aarnio@zmailer.org on Tue, Jan 09, 2001 at 02:21:56PM +0200
On Tue, Jan 09, 2001 at 02:21:56PM +0200, Matti Aarnio wrote:
[...]
>
> For IO on usual systems you have 32 bit address space PCI busmasters,
> so those can access only the lowest 4GB of address space, and to have
> a block of data in upper area, it needs to be "bounced", that is, CPU
> must copy it. Linux 2.4.0 system doesn't support 64-bit PCI addresses
> at 32-bit systems (not at 64-bit Alpha either, I recall.)
> On the other hand, Alpha systems and SPARC systems have IOMMU hardware,
> and we do support that (to some extent), but 32-bit intel world doesn't
> have similar things.
>
Hi Matti,
you are correct in saying that ia32 systems don't have IOMMU hardware, but
it's unfortunate that we don't support 64-bit PCI bus master cards, since
they're inexpensive and fairly common now. For instance, the Qlogic ISP SCSI
cards can do 64-bit addressing, as can many others. Has anybody taken a look
at enabling this ?
Tim
--
Tim Wright - timw@splhi.com or timw@aracnet.com or twright@us.ibm.com
IBM Linux Technology Center, Beaverton, Oregon
"Nobody ever said I was charming, they said "Rimmer, you're a git!"" RD VI
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next prev parent reply other threads:[~2001-01-09 16:29 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-01-09 4:11 Confirmation request about new 2.4.x. kernel limits Venkatesh Ramamurthy
2001-01-09 12:21 ` Matti Aarnio
2001-01-09 16:27 ` Tim Wright [this message]
2001-01-09 16:44 ` Andi Kleen
2001-01-09 16:50 ` Tim Wright
2001-01-10 13:16 ` Kurt Garloff
2001-01-09 14:05 ` Stephen C. Tweedie
-- strict thread matches above, loose matches on Subject: below --
2001-01-09 18:00 Venkatesh Ramamurthy
2001-01-09 17:35 Venkatesh Ramamurthy
2001-01-09 17:47 ` Andi Kleen
2001-01-09 15:15 Venkatesh Ramamurthy
2001-01-09 15:51 ` Andi Kleen
2001-01-04 11:50 A.D.F.
2001-01-04 11:23 ` Tigran Aivazian
2001-01-04 11:50 ` Anton Blanchard
2001-01-05 22:46 ` Pavel Machek
2001-01-09 14:03 ` Stephen C. Tweedie
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