From: Stefan Richter <stefanr@s5r6.in-berlin.de>
To: akepner@sgi.com
Cc: Andrew Morton <akpm@linux-foundation.org>,
grundler@parisc-linux.org, jbarnes@virtuousgeek.org, jes@sgi.com,
randy.dunlap@oracle.com, rdreier@cisco.com,
James.Bottomley@steeleye.com, davem@davemloft.net,
linux-kernel@vger.kernel.org
Subject: Re: [RFC] dma: passing "attributes" to dma_map_* routines
Date: Tue, 18 Dec 2007 17:50:42 +0100 [thread overview]
Message-ID: <4767FA62.9060002@s5r6.in-berlin.de> (raw)
In-Reply-To: <20071218001758.GO21916@sgi.com>
akepner@sgi.com wrote:
> Waaay back in October I sent some patches for passing additional
> attributes to the dma_map_* routines:
>
> http://marc.info/?l=linux-kernel&m=119137949604365&w=2
Do I understand correctly?: A device and the CPUs communicate via two
separate memory areas: A data buffer and a status FIFO. The NUMA
interconnect may reorder accesses of the device to the areas. (Write
accesses? Read accesses? Both?)
To ensure synchronization between device and CPUs, you want to mark a
memory area which is to be dma-mapped with a flag which says: "Writes
to the memory region will cause in-flight DMA to be flushed". Whose
writes? A write access from the device or a write access from a CPU?
--
Stefan Richter
-=====-=-=== ==-- =--=-
http://arcgraph.de/sr/
next prev parent reply other threads:[~2007-12-18 16:51 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-12-18 0:17 akepner
2007-12-18 16:50 ` Stefan Richter [this message]
2007-12-18 19:04 ` Roland Dreier
2007-12-18 20:07 ` akepner
2007-12-18 20:59 ` Stefan Richter
2007-12-18 21:09 ` Roland Dreier
2007-12-20 18:51 ` akepner
2007-12-20 19:06 ` akepner
2007-12-20 20:56 ` Benjamin Herrenschmidt
2007-12-21 18:00 ` akepner
2007-12-21 20:24 ` Stefan Richter
2007-12-21 21:31 ` Benjamin Herrenschmidt
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