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Re: [RFC] Extend remote protocol to allow symbol look-up service.
- To: msnyder at cygnus dot com
- Subject: Re: [RFC] Extend remote protocol to allow symbol look-up service.
- From: jlarmour at redhat dot com (Jonathan Larmour)
- Date: Wed, 18 Apr 2001 02:50:50 +0100
- Cc: gdb-patches at sources dot redhat dot com
- Newsgroups: cygnus.patches.gdb
- Organization: Red Hat UK Ltd.
In article <3ADCD1B8.772C5247@cygnus.com> you write:
>Surprising as it may seem, there are circumstances when a remote
>target stub may need to know the values of symbols in the debuggee.
>The case that I'm working from is multi-threaded debugging under
>Solaris and Linux. Both platforms make use of a debugging support
>library called libthread-db, which exports a debugging interface
>into the native thread library. It shields the debugger from
>knowledge about the thread library internals, but in return it
>needs to know the addresses of thread library data objects in the
>child, so that it can go rooting around in them.
I had a very similar situation with the libremote work I was doing,
which involved grubbing around in the target. For libremote
to be able to ask for a symbol would have made life much easier
than what I ended up implementing. libremote can be put in a
difficult situation - it neither has the knowledge of the debugger
nor the knowledge of the target/executing program. It is mostly
just a conduit.
>The scheme that I propose is this: whenever the debugger detects
>a new shared library being loaded in the remote child process,
>it will send a notification to the remote stub in the form of
>a 'Q' (miscelaneous set value) packet, like this:
>The target may as usual reply with an empty packet meaning
>"I don't understand", or with an "OK" acknowledgement, but
>in addition to those the target may reply with a request
>for the value of a symbol:
The situation I would have used it for had nothing to do with shared
libraries. I would much prefer it if the qSymbol could be received
at any point, and not just after a QSharedObject primitive.
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