Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759311Ab1FWL6q (ORCPT ); Thu, 23 Jun 2011 07:58:46 -0400 Received: from exprod5og101.obsmtp.com ([64.18.0.141]:53719 "EHLO exprod5og101.obsmtp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755812Ab1FWL6p (ORCPT ); Thu, 23 Jun 2011 07:58:45 -0400 X-Greylist: delayed 303 seconds by postgrey-1.27 at vger.kernel.org; Thu, 23 Jun 2011 07:58:44 EDT Message-ID: <4E032940.5010205@ge.com> Date: Thu, 23 Jun 2011 12:53:36 +0100 From: Martyn Welch Organization: GE Intelligent Platforms User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.2.17) Gecko/20110424 Thunderbird/3.1.10 MIME-Version: 1.0 To: Ralf Baechle CC: Greg Kroah-Hartman , devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org, David Howells , linux-m32r@ml.linux-m32r.org, linux-m32r-ja@ml.linux-m32r.org, linux-am33-list@redhat.com, Paul Mundt , linux-sh@vger.kernel.org, Chris Metcalf , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, linux-arch@vger.kernel.org Subject: Re: [PATCH] STAGING: Comedi: Build only on arches providing PAGE_KERNEL_NOCACHE References: <20110623114536.GA14011@linux-mips.org> In-Reply-To: <20110623114536.GA14011@linux-mips.org> X-Enigmail-Version: 1.1.2 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-OriginalArrivalTime: 23 Jun 2011 11:51:13.0898 (UTC) FILETIME=[DA4B94A0:01CC319B] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2576 Lines: 56 On 23/06/11 12:45, Ralf Baechle wrote: > On architectures that don't define PAGE_KERNEL_NOCACHE, the Comedi driver turns > into tragedy: > > CC [M] drivers/staging/comedi/drivers.o > drivers/staging/comedi/drivers.c: In function ‘comedi_buf_alloc’: > drivers/staging/comedi/drivers.c:505:41: error: ‘PAGE_KERNEL_NOCACHE’ undeclared (first use in this function) > drivers/staging/comedi/drivers.c:505:41: note: each undeclared identifier is rep orted only once for each function it appears in > make[3]: *** [drivers/staging/comedi/drivers.o] Error 1 > > Restrict the driver to only those architectures that define PAGE_KERNEL_NOCACHE. > > PAGE_KERNEL_NOCACHE is a kludge - some system architectures such as SGI IP27 > are even uable to offer uncached operation - at least in the way an unwitting > driver might assume. I haven't looked in details how the driver is using > the area vmaped with PAGE_KERNEL_NOCACHE but maybe doing it XFS-style using > cached memory and the flush_kernel_vmap_range / invalidate_kernel_vmap_range > APIs in conjunction with the DMA API is a practical alternative. > > Signed-off-by: Ralf Baechle > > drivers/staging/comedi/Kconfig | 1 + > 1 files changed, 1 insertions(+), 0 deletions(-) > > diff --git a/drivers/staging/comedi/Kconfig b/drivers/staging/comedi/Kconfig > index 1502d80..bccdc12 100644 > --- a/drivers/staging/comedi/Kconfig > +++ b/drivers/staging/comedi/Kconfig > @@ -2,6 +2,7 @@ config COMEDI > tristate "Data acquisition support (comedi)" > default N > depends on m > + depends on BROKEN || FRV || M32R || MN10300 || SUPERH || TILE || X86 I'm sure I got comedi to compile on a 32-bit PPC board not that long ago. Has something changed, or is this just not an exhaustive list? > ---help--- > Enable support a wide range of data acquisition devices > for Linux. > _______________________________________________ > devel mailing list > devel@linuxdriverproject.org > http://driverdev.linuxdriverproject.org/mailman/listinfo/devel -- Martyn Welch (Principal Software Engineer) | Registered in England and GE Intelligent Platforms | Wales (3828642) at 100 T +44(0)127322748 | Barbirolli Square, Manchester, E martyn.welch@ge.com | M2 3AB VAT:GB 927559189 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/