Date: Mon, 15 Jun 2009 10:13:55 +0200
From: Joerg Roedel <joerg.roedel@amd.com>
To: Stefan Richter <stefanr@s5r6.in-berlin.de>
CC: Ben Dooks <ben-linux@fluff.org>, linux-kernel@vger.kernel.org
Subject: Re: dma-debug: check_for_stack background?
Message-ID: <20090615081355.GA5139@amd.com>
References: <4A3547DD.2010809@s5r6.in-berlin.de> <20090614212018.GD20442@fluff.org.uk> <4A356F0E.9020809@s5r6.in-berlin.de>
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On Sun, Jun 14, 2009 at 11:43:42PM +0200, Stefan Richter wrote:
> Ben Dooks wrote:
>> On Sun, Jun 14, 2009 at 08:56:29PM +0200, Stefan Richter wrote:
>>> the DMA debug facility warns  about mappings of on-stack memory.  
>>> What's the problem with that?
> ...
>> I'm not sure if it is possible on all architectures, however the
>> DMA mapping documentation prohibts the use of stack memory.
>
> Ah, it has all been documented in plain sight for ages.  Thanks for the  
> pointer.

Problem is that the stack might go away or could be otherwise reused
while the DMA is in-flight. This could cause really hard to debug
problems.

	Joerg

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