linux-kernel - Re: mmap'ed memory in core files ?

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Message-ID: <517f3f820807011116g6ce1b3e1qf166070f7a4c523f@mail.gmail.com>
Date:	Tue, 1 Jul 2008 20:16:11 +0200
From:	"Michael Kerrisk" <mtk.manpages@...il.com>
To:	"Philippe De Muyter" <phdm@...qel.be>
Cc:	linux-kernel@...r.kernel.org,
	libdc1394-devel@...ts.sourceforge.net,
	"Michael Kerrisk" <mtk.manpages@...il.com>
Subject: Re: mmap'ed memory in core files ?

On 7/1/08, Philippe De Muyter <phdm@...qel.be> 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

Cheers,

Michael
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