From: Alan Cox <alan@linux.intel.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Alessandro Rubini <ru@gnudd.com>,
fujita.tomonori@lab.ntt.co.jp, tglx@linutronix.de,
mingo@redhat.com, hpa@zytor.com, x86@kernel.org,
linux-kernel@vger.kernel.org, giancarlo.asnaghi@st.com,
maddalena.brattoli@st.com
Subject: Re: a question on DMA and remapping
Date: Tue, 22 Nov 2011 23:00:19 +0000 [thread overview]
Message-ID: <20111122230019.3304ecdf@bob.linux.org.uk> (raw)
In-Reply-To: <20111117154729.afa24f07.akpm@linux-foundation.org>
> Generalising the existing code to cover more cases isn't a bad thing
> to do. Others might be able to use it, and they surely won't be able
> to use any cloned-and-owned swiotlb.c.
If you look on the kernel list there has also been some discussion and
work recently towards removing a lot of the duplication between the
iommu devices.
I think really you need to be an actual iommu instance because in
reality you are. Trying to fudge it any other way breaks the moment
someone tries to do a device to device DMA transfer because your
bus/phys mapping seen from your device and the bus/phys mapping seen
from another device into your device do not match as I understand it.
Alan
prev parent reply other threads:[~2011-11-22 22:48 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-17 23:30 a question on DMA and remapping Alessandro Rubini
2011-11-17 23:47 ` Andrew Morton
2011-11-22 23:00 ` Alan Cox [this message]
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