Re: Partial cores using Linux "pipe" core_pattern

[Andreas Schwab <schwab@linux-m68k.org>]

Paul Smith <psmith@gnu.org> writes:

> On Mon, 2009-05-18 at 09:25 +0200, Andi Kleen wrote:
>> Paul Smith <psmith@gnu.org> writes:
>> >
>> > Does anyone have any thoughts about where I can look next to try to
>> > figure out what's going on?  Ideas or knowledge about limitations of the
>> > kernel's core_pattern pipe capability, such as timing issues etc., that
>> > might be leaving me with short cores?
>> 
>> Sounds more like a kernel problem to me. It would be good if you
>> could find out in what way the cores are truncated, then do a proper
>> kernel bug report.
>> 
>> Or add printks to the kernel coredumper and try to figure out this
>> way where/why it stops.
>
> Heh, I was afraid you'd say that :-).  OK, I'll dig into the kernel
> coredumper and add some printks etc.

Apparently the ELF core dumper cannot handle short writes (see
dump_write in fs/binfmt_elf.c).  You should probably use a read buffer
of at least a page, which is the most the kernel tries to write at once.

Andreas.

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Andreas Schwab, schwab@linux-m68k.org
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