From: Grant Grundler <iod00d@hp.com>
To: linux-ia64@vger.kernel.org
Subject: Re: dma restriction on Itanium 2
Date: Sat, 17 Jan 2004 02:14:22 +0000 [thread overview]
Message-ID: <20040117021422.GG18103@cup.hp.com> (raw)
In-Reply-To: <1074304095.6384.13.camel@kbiswas-dt.s2iotech.com>
On Fri, Jan 16, 2004 at 05:48:15PM -0800, Kallol Biswas wrote:
> We have been seeing a problem on itanium 2 running linux 2.4.21-4.EL
> with our 10GB ethernet card.
> The error is PCI related. On PARISC systems the DMA address could not
> span page boundary due to hardware limitation,
Which HW limitation on parisc?
Are you talking about under HPUX?
Calling pci_map_single() can map up to 64-pages under parisc-linux.
(And that's a semi-arbitrary SW limit I designed into the implementation)
pci_alloc_consistent() has the same limitation since it uses
pci_map_single().
> do we have the same limitation on Itanium 2 systems also?
Under linux ZX1 DMA support has very similar constraints
HW-wise as PARISC *except* for 64-bit capable devices.
64-bit devices are not limited to 64-pages on ZX1.
> If the transmit or receive
> descriptors take more than a page then they should be aligned such a way
> that DMA does not happen over a page right?
transmit and recieve descriptors should be using memory allocated
with pci_alloc_consistent(). I'm not aware of any page boundary
limitation there. What's missing in 2.4.X is the ability
to set 64-bit attribute for PCI consistent memory.
grant
next prev parent reply other threads:[~2004-01-17 2:14 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-01-17 1:48 dma restriction on Itanium 2 Kallol Biswas
2004-01-17 2:14 ` Grant Grundler [this message]
2004-01-17 3:58 ` Grant Grundler
2004-01-17 18:47 ` Christian Hinkelbein
2004-01-19 6:14 ` Grant Grundler
2004-01-19 16:00 ` Alex Williamson
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