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Re: dlmopen and core dumps
- From: Jan Kratochvil <jan dot kratochvil at redhat dot com>
- To: "Carlos O'Donell" <carlos at systemhalted dot org>
- Cc: Pedro Alves <palves at redhat dot com>, Roland McGrath <roland at hack dot frob dot com>, libc-alpha at sourceware dot org, gbenson at redhat dot com
- Date: Thu, 3 Jan 2013 18:55:35 +0100
- Subject: Re: dlmopen and core dumps
- References: <20121105132108.GA4305@redhat.com><CAE2sS1j8pNMhgunxNHvCofR-TuiJYk9HVTWk5OYz0MQN2_GuDg@mail.gmail.com><20121213214047.4D5652C0BF@topped-with-meat.com><50CB55A5.2020007@redhat.com><CAE2sS1gnk0vCgWFpmxQVLfcNOGYU3SRXU-ZtpfBU4JFZoPo2tw@mail.gmail.com><50CB6100.7070100@redhat.com><CAE2sS1iRo8_Z1zCkGN==cU0b=-zy_4o1GpTxk02Rpq+QoFhVNw@mail.gmail.com><20121219180552.GA19512@host2.jankratochvil.net><50D20572.70002@systemhalted.org>
On Wed, 19 Dec 2012 19:20:34 +0100, Carlos O'Donell wrote:
> At present there appear to be three solutions:
>
> (1) Investigate r_debug solution, it's incremental, and ugly, but we
> know it works.
>
> (2) Investigate a python based solution, usable by gdb or other
> tools via a python interpreter.
>
> (3) Investigate a DWARF based declarative solution.
Posting only for the record as it seems now GDB is not going to implement this
discussed dlmopen interface as there are no users of dlmopen.
There is also:
(4) Provide new ELF symbols of ld.so such as "_r_debug_version2" describing
some new extensions. Possibly to provide ELF symbols with offsets etc.
There already exist such symbols like "_thread_db_*" but those are private
for libthread_db which is problematic to use. "_r_debug_version2" could
be an official ABI to be directly accessed by debuggers.
But this has a problem it no longer works after stripping ld.so which
happens for some users. Maybe to put such symbols to .dynsym?
The same stripping problem already affects libthread_db:
http://sourceware.org/glibc/wiki/Development_Todo/Master?action=diff&rev2=40&rev1=39
I understand it is not nice but it is Very simple compared to (2) or (3).
Jan