From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Alan Shih <alan@storlinksemi.com>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: Question regarding DMA xfer to user space directly
Date: 08 Jul 2003 16:22:23 +0100 [thread overview]
Message-ID: <1057677742.4358.36.camel@dhcp22.swansea.linux.org.uk> (raw)
In-Reply-To: <ODEIIOAOPGGCDIKEOPILIEODCLAA.alan@storlinksemi.com>
On Maw, 2003-07-08 at 15:50, Alan Shih wrote:
> Is there a provision in MM for DMA transfer to user space directly without
> allocating a kernel buffer?
Yes. Its used both for O_DIRECT I/O (direct to disk I/O from userspace)
and for things like tv capture cards. The kernel allows a driver to pin
user pages and obtain mappings for them. Note that for large systems
user pages may be above the 32bit boundary so you need DAC capable
hardware to get the best results
next prev parent reply other threads:[~2003-07-08 15:12 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-07-08 14:50 Question regarding DMA xfer to user space directly Alan Shih
2003-07-08 15:22 ` Alan Cox [this message]
2003-07-09 17:35 ` Alan Shih
[not found] <3C6BEE8B5E1BAC42905A93F13004E8AB034C5623@mailse01.axis.se>
2003-07-10 5:22 ` Mikael Starvik
2003-07-10 10:26 ` Jens Axboe
2003-07-10 20:55 Lee, Shuyu
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