From: Mahesh <maheshk@cdac.in>
To: David Miller <davem@davemloft.net>
Cc: linux-kernel@vger.kernel.org, kernelnewbies@nl.linux.org
Subject: Re: [HOWTO] accessing the DMA mapped data
Date: Thu, 10 May 2007 17:11:17 +0530 [thread overview]
Message-ID: <464304DD.9070600@cdac.in> (raw)
In-Reply-To: <20070510.043233.08323827.davem@davemloft.net>
Hi,
> You haven't given an example of where this might actually happen.
>
> The driver is where the DMA mappings almost always occur because
> that is the layer that knows the bus technology and therefore
> the correct DMA interfaces to call.
>
> What kind of driver do you have and what is this upper layer
> doing the mappings for you but not giving you a pointer to
> the kernel buffer as well?
>
Here I am dealing with a infiniband (see www.openfabrics.org) network
device driver. The layer above the
driver is the standard infiniband core interface. Now I have a situation
where I need to peek into the packets
and do some modifications(some hacking). So I just want know whether I
can access the original data region
using the bus address generated by the dma_map_single.
FYI, architecture I am working on is x86_64.
-Mahesh
next prev parent reply other threads:[~2007-05-10 11:39 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-05-10 7:58 [HOWTO] accessing the DMA mapped data Mahesh
2007-05-10 8:47 ` David Miller
2007-05-10 11:19 ` Mahesh
2007-05-10 11:32 ` David Miller
2007-05-10 11:41 ` Mahesh [this message]
2007-05-10 11:47 ` David Miller
2007-05-11 15:42 ` Muli Ben-Yehuda
2007-05-10 18:27 ` Roland Dreier
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