From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932739AbcGOLmr (ORCPT ); Fri, 15 Jul 2016 07:42:47 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:54929 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932590AbcGOLmq (ORCPT ); Fri, 15 Jul 2016 07:42:46 -0400 Date: Fri, 15 Jul 2016 20:42:54 +0900 From: Greg Kroah-Hartman To: Rich Felker Cc: "Hans J. Koch" , linux-kernel@vger.kernel.org Subject: Re: [PATCH RFC] uio: allow use on nommu systems Message-ID: <20160715114254.GC27936@kroah.com> References: <20160715005306.GA16591@brightrain.aerifal.cx> <20160715014237.GC5791@kroah.com> <20160715015829.GR15995@brightrain.aerifal.cx> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160715015829.GR15995@brightrain.aerifal.cx> User-Agent: Mutt/1.6.2 (2016-07-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 14, 2016 at 09:58:29PM -0400, Rich Felker wrote: > On Fri, Jul 15, 2016 at 10:42:37AM +0900, Greg Kroah-Hartman wrote: > > On Thu, Jul 14, 2016 at 08:53:06PM -0400, Rich Felker wrote: > > > mmap of uio devices does not seem to work without further > > > nommu-specific support, but interrupt handling already works, and > > > userspace drivers for nommu systems can simply use physical mmio > > > addresses from userspace directly anyway without mmap. > > > > > > Signed-off-by: Rich Felker > > > --- > > > > > > I don't particularly expect this to be accepted upstream as-is, but > > > since we're actually trying to use the UIO subsystem on nommu (J2), > > > I'd like to start a discussion of what an acceptable patch would > > > entail. > > > > > > The uio_pdrv_genirq driver was tested on J2 with this patch and > > > interrupt handling works as expected. > > > > > > drivers/uio/Kconfig | 1 - > > > 1 file changed, 1 deletion(-) > > > > > > diff --git a/drivers/uio/Kconfig b/drivers/uio/Kconfig > > > index 52c98ce..387b2bb 100644 > > > --- a/drivers/uio/Kconfig > > > +++ b/drivers/uio/Kconfig > > > @@ -1,6 +1,5 @@ > > > menuconfig UIO > > > tristate "Userspace I/O drivers" > > > - depends on MMU > > > > This doesn't seem to do much, don't you need to modify uio-specific > > drivers? Or given that the core uio code doesn't rely on mmu, is this > > safe? > > As noted above, mmap of the device does not work (returns error); I > don't understand why. Try working that out and then we can talk :) thanks, greg k-h