Messages in this thread | | | From | "Mikael Starvik" <> | Subject | RE: Question regarding DMA xfer to user space directly | Date | Thu, 10 Jul 2003 07:22:40 +0200 |
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Hi,
Use map_user_kiobuf to do this. There are several examples in the kernel tree. One of the simplest may be arch/cris/drivers/examples/kiobuftest.c.
/Mikael
-----Original Message----- From: linux-kernel-owner@vger.kernel.org [mailto:linux-kernel-owner@vger.kernel.org] On Behalf Of Alan Shih Sent: Wednesday, July 09, 2003 7:35 PM To: Alan Cox Cc: Linux Kernel Mailing List Subject: RE: Question regarding DMA xfer to user space directly
Next question would be what are the steps that the driver need to ping user pages before setting up the xfer?
Thanks.
-----Original Message----- From: Alan Cox [mailto:alan@lxorguk.ukuu.org.uk] Sent: Tuesday, July 08, 2003 8:22 AM To: Alan Shih Cc: Linux Kernel Mailing List Subject: Re: Question regarding DMA xfer to user space directly
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
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