From: Or Gerlitz <ogerlitz-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
To: Klaus Wacker <Klaus.Wacker-tA70FqPdS9bQT0dZR+AlfA@public.gmane.org>
Cc: linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: Linux DMA address
Date: Mon, 2 Jul 2012 16:53:52 +0300 [thread overview]
Message-ID: <4FF1A7F0.10208@mellanox.com> (raw)
In-Reply-To: <OF0BBAC7B2.370E3DEF-ONC1257A2F.003DED12-C1257A2F.00407B62-tA70FqPdS9bQT0dZR+AlfA@public.gmane.org>
On 7/2/2012 2:44 PM, Klaus Wacker wrote:
> [...] So whats the nature of the returned DMA address of ib_dma_map_single and can we
> assume that it is the same value on different devices on one system?
Currently, over all IB drivers/devices except for ipath and qib,
ib_dma_map_single is just plain dma_map_single, so your questions
relates directly to the Linux DMA mapping API (and BTW - the answer is
YES, in the general case you must use a DMA address you were provided
when calling dma_map_single with device being X only for transactions
carried over X). For those devices that hack ib_dma_map_single, it might
be possible to use address provided from device X over device Y, but
this is a hack, and I would strongly recommend not to have it in you code.
Or.
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next prev parent reply other threads:[~2012-07-02 13:53 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-02 11:44 Linux DMA address Klaus Wacker
[not found] ` <OF0BBAC7B2.370E3DEF-ONC1257A2F.003DED12-C1257A2F.00407B62-tA70FqPdS9bQT0dZR+AlfA@public.gmane.org>
2012-07-02 13:53 ` Or Gerlitz [this message]
[not found] ` <4FF1A7F0.10208-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
2012-07-03 13:37 ` Klaus Wacker
[not found] ` <OF2C9BED9D.50BF4649-ONC1257A30.004A568D-C1257A30.004ADEF1-tA70FqPdS9bQT0dZR+AlfA@public.gmane.org>
2012-07-03 14:03 ` Or Gerlitz
2012-07-03 14:34 ` Roland Dreier
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