Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753565AbYGBLEu (ORCPT ); Wed, 2 Jul 2008 07:04:50 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755364AbYGBLEl (ORCPT ); Wed, 2 Jul 2008 07:04:41 -0400 Received: from mail.macqel.be ([194.78.208.39]:11988 "EHLO mail.macqel.be" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755314AbYGBLEl (ORCPT ); Wed, 2 Jul 2008 07:04:41 -0400 Date: Wed, 2 Jul 2008 13:04:37 +0200 From: Philippe De Muyter To: Michael Kerrisk Cc: Michael Kerrisk , linux-kernel@vger.kernel.org, libdc1394-devel@lists.sourceforge.net, hidehiro.kawai.ez@hitachi.com, linux1394-devel@lists.sourceforge.net Subject: Re: mmap'ed memory in core files ? Message-ID: <20080702110437.GB6761@frolo.macqel> References: <20080701132149.GA32510@frolo.macqel> <517f3f820807011116g6ce1b3e1qf166070f7a4c523f@mail.gmail.com> <20080702105027.GA1111@frolo.macqel> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.16 (2007-06-09) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3248 Lines: 78 [CC+= linux1394-devel@lists.sourceforge.net] On Wed, Jul 02, 2008 at 12:58:05PM +0200, Michael Kerrisk wrote: > [CC+= hidehiro.kawai.ez@hitachi.com] > > On Wed, Jul 2, 2008 at 12:50 PM, Philippe De Muyter wrote: > > Hi Michael, > > > > On Tue, Jul 01, 2008 at 08:16:11PM +0200, Michael Kerrisk wrote: > >> On 7/1/08, Philippe De Muyter wrote: > >> > Hello everybody, > >> > > >> > I develop video acquisition software using the video1394 interface. > >> > The images grabbed by the camera and iee1394 bus are kept in kernel > >> > memory and made available to the user program through a mmap call done > >> > in the libdc1394 library : > >> > > >> > dma_ring_buffer= mmap(0, vmmap.nb_buffers * vmmap.buf_size, > >> > PROT_READ|PROT_WRITE,MAP_SHARED, craw->capture.dma_fd, 0); > >> > > >> > Sometimes, my program crashes and produces a core file :) It seems to > >> > me that the core file does not contain the mmap'ed memory and hence > >> > I cannot replay my program with the same image for debugging purpose. > >> > > >> > Is it possible to configure the kernel through /proc, or through the mmap > >> > system call to have that mmapped segment in the core file, or do I need > >> > to modify the kernel itself to obtain the behaviour I want ? If I > >> > need to modify the kernel, can some kind soul provide me some pointers ? > >> > >> > >> Have a look at the section "Controlling which mappings are written to > >> the core dump" in a recent core.5 man page: > >> http://www.kernel.org/doc/man-pages/online/pages/man5/core.5.html > > > > thanks for the info. I didn't know about /proc/PID/coredump_filter. > > > > that part was promising : > > > > bit 2 Dump file-backed private mappings. > > bit 3 Dump file-backed shared mappings. > > > > The default value of coredump_filter is 0x3; this reflects traditional > > Linux behavior and means that only anonymous memory segments are dumped. > > > > Unfortunately, the part that applies to me (I have tested it) is the next one : > > > > Memory-mapped I/O pages such as frame buffer are never dumped, [...], > > regardless of the coredump_filter value. > > > > Is that a design decision, or a mere finding of the way it is implemented > > now ? > > > > So, back to my original question : > > > > Can some kind soul provide me some pointers to the way I should modify > > the kernel to make the inclusion of the video1394 mmapped segment in > > core files possible ? > > Perhaps Hidehiro, who wrote the coredump_filter feature, can provide insight. > > Cheers, > > Michael > > -- > Michael Kerrisk > Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ > man-pages online: http://www.kernel.org/doc/man-pages/online_pages.html > Found a bug? http://www.kernel.org/doc/man-pages/reporting_bugs.html -- Philippe De Muyter phdm at macqel dot be Tel +32 27029044 Macq Electronique SA rue de l'Aeronef 2 B-1140 Bruxelles Fax +32 27029077 -- 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/