From: Tom Tromey <tom@tromey.com>
To: Simon Sobisch via Gdb <gdb@sourceware.org>
Cc: Simon Sobisch <simonsobisch@gnu.org>
Subject: Re: debugging coredumps with the help of libraries (for example to pretty-print)
Date: Mon, 10 May 2021 10:38:34 -0600 [thread overview]
Message-ID: <877dk68rxx.fsf@tromey.com> (raw)
In-Reply-To: <bc6c217c-59d4-55c8-a517-da24be2b8763@gnu.org> (Simon Sobisch via Gdb's message of "Thu, 6 May 2021 21:00:58 +0200")
>>>>> "Simon" == Simon Sobisch via Gdb <gdb@sourceware.org> writes:
Simon> But when I now create a core-dump (gcore dumpfile) and then start gdb
Simon> with to debug that I see the full state and local variables - but none
Simon> of those pretty printers work, resulting in "You can't do that without
Simon> a process to debug." messages.
These are also somewhat dangerous to use. I think there have been
reports of gdb crashes when calling inferior functions from
pretty-printers. So, normally I recommend against doing this kind of
thing; though if it works for you, great.
It's possible some code in the Python layer isn't careful about using
frame-ids instead of frames. That would cause bugs. Also inferior
calls can cause other threads to run, which can be super confusing.
Simon> Is it possible to let GDB itself load the libraries and pass resolve
Simon> the string values that way (or somehow start a "new" process along
Simon> with the coredump only for letting it print the values from the
Simon> coredump data)?
There was a old wish list item to resurrect a core file and turn it into
a running process. Maybe this is possible, maybe not. As far as I
know, nobody has ever really tried. Anyway, it doesn't exist, so the
current answer is 'no'.
Simon> If not then it is either "disable the pretty printing when a coredump
Simon> is processed" [what is the best check for that in a python extension
Simon> btw?] or try to re-implement the string function completely in python.
I would normally just reimplement it in Python.
Tom
prev parent reply other threads:[~2021-05-10 16:38 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-06 19:00 Simon Sobisch
2021-05-06 21:45 ` David Blaikie
2021-05-10 16:38 ` Tom Tromey [this message]
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