From mboxrd@z Thu Jan 1 00:00:00 1970 From: Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= Date: Wed, 21 May 2008 08:05:03 +0000 Subject: Re: [PATCH 00/03][RFC] Reusable UIO Platform Driver Message-Id: <20080521080503.GA28751@digi.com> List-Id: References: <20080520105132.1474.73941.sendpatchset@rx1.opensource.se> <20080520210713.GE3220@local> <20080521064938.GA11580@digi.com> <20080521074950.GA27310@linux-sh.org> In-Reply-To: <20080521074950.GA27310@linux-sh.org> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable To: Paul Mundt , Magnus Damm , "Hans J. Koch" , linux-kernel@vger.kernel.org, gregkh@suse.de, linux-sh@vger.kernel.org Paul Mundt wrote: > On Wed, May 21, 2008 at 08:49:38AM +0200, Uwe Kleine-K?nig wrote: > > Magnus Damm wrote: > > > Extending uio_pdrv driver with a chunk of physically > > > contiguous memory isn't a big deal though. > > I wonder how you use that memory. Isn't it just some kind of shared > > memory? If so, why not use normal shared memory? Do you really need > > that? > >=20 > Physically contiguous memory is a real requirement, especially for DMA. > I'm not sure what's confusing about that? I got that, yes. The problem is I don't see how you can use it for DMA. The physical address is stored in info->mem[$last].internal_addr and if there is a way to access that variable from user space, I don't see it and would appretiate a hint. Sorry for not expressing my concern more clear at the first go. I hope it's understandable now. @Magnus: Maybe you can provide the userspace part of the driver? How is that mapping used there? Best regards Uwe --=20 Uwe Kleine-K=F6nig, Software Engineer Digi International GmbH Branch Breisach, K=FCferstrasse 8, 79206 Breisach, = Germany Tax: 315/5781/0242 / VAT: DE153662976 / Reg. Amtsgericht Dortmund HRB 13962