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Date: Wed, 22 Mar 2006 10:24:07 -0800
From: Jason Evans <jasone@FreeBSD.org>
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To: John Baldwin <jhb@freebsd.org>
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Cc: John-Mark Gurney <gurney_j@resnet.uoregon.edu>, freebsd-current@freebsd.org
Subject: Re: core dumps are HUGE...
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John Baldwin wrote:
> I think the better path is to provide sparse coredumps.  I.e., when dumping a
> core, leave the parts of the process map that are mapped but have no backing
> store yet (b/c the pages haven't been touched) sparse by not writing to them,
> but just seeking past them.  This doesn't require complicating the malloc
> implementation just for the sake of a core dump on a CF device.

I like this solution too.  I'm sure there are people who could make this 
change with much less effort than me though. =)

It looks like the necessary changes are in 
sys/kern/imgact_elf.c:coredump().  That code writes a segment at a time, 
but it would need to be modified to look at the process's page map and 
write segments piecemeal.

Jason