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From: Robert Hancock <hancockr@shaw.ca>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: linuxppc-dev@ozlabs.org,
	Stefan Richter <stefanr@s5r6.in-berlin.de>,
	stable@kernel.org, linux-kernel@vger.kernel.org,
	Olaf Hering <olh@suse.de>
Subject: Re: [PATCH 2.6.22.y] ieee1394: revert "sbp2: enforce	32bit	DMA	mapping"
Date: Mon, 06 Aug 2007 16:35:25 -0600	[thread overview]
Message-ID: <46B7A22D.4030909@shaw.ca> (raw)
In-Reply-To: <1186439529.938.95.camel@localhost.localdomain>

Benjamin Herrenschmidt wrote:
> On Mon, 2007-08-06 at 16:25 -0600, Robert Hancock wrote:
>>> Anyway.  For now I will simply go with what 2.6.23-rc has and what
>>> 2.6.21 had:  No dma_set_mask anywhere in the 1394 subsystem.  We can
>>> revisit this whenever an actual need arises.
>> Not sure this is a very good idea. This seems rather likely to fail on
>> x86_64 machines with >4GB of RAM for example.. 
> 
> Would it ? Isn't the default DMA mask for PCI devices set to 32 bits
> anyway ? In which case, swiotlb will take care of the matter.
> 
> Cheers,
> Ben.

Hmm, that's true, yes. Suppose it shouldn't be a problem then.

I would agree, though, that sbp2 isn't really the place for setting 
this, since the DMA mask is presently a property of the device, not of 
the user..

-- 
Robert Hancock      Saskatoon, SK, Canada
To email, remove "nospam" from hancockr@nospamshaw.ca
Home Page: http://www.roberthancock.com/

WARNING: multiple messages have this Message-ID (diff)
From: Robert Hancock <hancockr@shaw.ca>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Stefan Richter <stefanr@s5r6.in-berlin.de>,
	Olaf Hering <olh@suse.de>,
	linuxppc-dev@ozlabs.org, stable@kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2.6.22.y] ieee1394: revert "sbp2: enforce	32bit	DMA	mapping"
Date: Mon, 06 Aug 2007 16:35:25 -0600	[thread overview]
Message-ID: <46B7A22D.4030909@shaw.ca> (raw)
In-Reply-To: <1186439529.938.95.camel@localhost.localdomain>

Benjamin Herrenschmidt wrote:
> On Mon, 2007-08-06 at 16:25 -0600, Robert Hancock wrote:
>>> Anyway.  For now I will simply go with what 2.6.23-rc has and what
>>> 2.6.21 had:  No dma_set_mask anywhere in the 1394 subsystem.  We can
>>> revisit this whenever an actual need arises.
>> Not sure this is a very good idea. This seems rather likely to fail on
>> x86_64 machines with >4GB of RAM for example.. 
> 
> Would it ? Isn't the default DMA mask for PCI devices set to 32 bits
> anyway ? In which case, swiotlb will take care of the matter.
> 
> Cheers,
> Ben.

Hmm, that's true, yes. Suppose it shouldn't be a problem then.

I would agree, though, that sbp2 isn't really the place for setting 
this, since the DMA mask is presently a property of the device, not of 
the user..

-- 
Robert Hancock      Saskatoon, SK, Canada
To email, remove "nospam" from hancockr@nospamshaw.ca
Home Page: http://www.roberthancock.com/



  reply	other threads:[~2007-08-06 22:35 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <fa.Qn3Snqoik3hhnxcA6HqjGV0Yzck@ifi.uio.no>
2007-08-04 17:14 ` [PATCH 2.6.22.y] ieee1394: revert "sbp2: enforce 32bit DMA mapping" Robert Hancock
2007-08-04 17:30   ` Stefan Richter
2007-08-04 17:30     ` Stefan Richter
2007-08-05  0:15     ` Benjamin Herrenschmidt
2007-08-05  0:15       ` Benjamin Herrenschmidt
2007-08-05  7:54       ` Stefan Richter
2007-08-05  7:54         ` Stefan Richter
2007-08-05 22:04         ` Benjamin Herrenschmidt
2007-08-05 22:04           ` Benjamin Herrenschmidt
2007-08-06 13:51           ` Olaf Hering
2007-08-06 13:51             ` Olaf Hering
2007-08-06 21:47             ` Benjamin Herrenschmidt
2007-08-06 21:47               ` Benjamin Herrenschmidt
2007-08-06 22:22               ` Stefan Richter
2007-08-06 22:22                 ` Stefan Richter
2007-08-06 22:25                 ` Robert Hancock
2007-08-06 22:25                   ` Robert Hancock
2007-08-06 22:32                   ` Benjamin Herrenschmidt
2007-08-06 22:32                     ` Benjamin Herrenschmidt
2007-08-06 22:35                     ` Robert Hancock [this message]
2007-08-06 22:35                       ` Robert Hancock
2007-08-06 22:59                       ` Stefan Richter
2007-08-06 22:59                         ` Stefan Richter
2007-08-06 22:48                   ` Stefan Richter
2007-08-06 22:48                     ` Stefan Richter
2007-08-07  2:18                     ` Andi Kleen
2007-08-07  2:18                       ` Andi Kleen
2007-08-06 22:29                 ` Benjamin Herrenschmidt
2007-08-06 22:29                   ` Benjamin Herrenschmidt
2007-08-06 11:58         ` Olaf Hering
2007-08-06 11:58           ` Olaf Hering
2007-08-06 21:43           ` Benjamin Herrenschmidt
2007-08-06 21:43             ` Benjamin Herrenschmidt
2007-08-06 22:05             ` [PATCH] powerpc: Fix initialization and usage of dma_mask Benjamin Herrenschmidt
2007-08-06 22:05               ` Benjamin Herrenschmidt
2007-08-06 22:30               ` Olaf Hering
2007-08-06 22:30                 ` Olaf Hering
2007-08-04 16:39 [PATCH 2.6.22.y] ieee1394: revert "sbp2: enforce 32bit DMA mapping" Stefan Richter

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