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From: Clemens Ladisch <clemens@ladisch.de>
To: Peter Hurley <peter@hurleysoftware.com>
Cc: Stefan Richter <stefanr@s5r6.in-berlin.de>,
	linux1394-devel@lists.sourceforge.net,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] firewire: Enable physical DMA above 4GB
Date: Fri, 29 Mar 2013 12:19:44 +0100	[thread overview]
Message-ID: <515578D0.9090701@ladisch.de> (raw)
In-Reply-To: <1364554250.3559.61.camel@thor.lan>

Peter Hurley wrote:
> On Fri, 2013-03-29 at 11:44 +0100, Stefan Richter wrote:
>>> On Mar 26 Peter Hurley wrote:
>>>> The FW643e-2 is natively PCIe (not behind a bridge) and supports phys
>>>> DMA past 4GB (the datasheet says all 48 bits but I can only test it out
>>>> to 10GB).
>>>>
>>>> I thought the FW643e was as well? You'll have to test that out :)
>>
>> Does lspci or something similar show which PCI devices are capable of 64 bit
>> wide addressing?
>
> Not definitively.
>
> Usually (but not always), if the host registers are 64-bit addressable,
> then the device supports DAC.

DACs are a feature of conventional PCI.

All PCI Express devices are 64-bit addressable.  In the lspci output, PCIe
devices have the "Express" capability.

However, whether a device can *generate* 64-bit DMA requests is completely
device-specific.


Regards,
Clemens

  reply	other threads:[~2013-03-29 11:21 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-03-26 14:22 [PATCH] firewire: Enable physical DMA above 4GB Peter Hurley
2013-03-26 16:12 ` Clemens Ladisch
2013-03-26 17:04   ` Peter Hurley
2013-03-26 18:22     ` Clemens Ladisch
2013-03-26 18:56 ` Stefan Richter
2013-03-26 19:08   ` Peter Hurley
2013-03-26 20:35     ` Stefan Richter
2013-03-29 10:44       ` Stefan Richter
2013-03-29 10:50         ` Peter Hurley
2013-03-29 11:19           ` Clemens Ladisch [this message]
2013-03-29 11:31             ` Peter Hurley

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