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From: Jim Blandy <>
To: Vinu Dev <>
Subject: Re: Help required on rda [FRV]
Date: Mon, 16 May 2005 21:14:00 -0000	[thread overview]
Message-ID: <vt23bsm6fo2.fsf@zenia.home> (raw)
In-Reply-To: <>

Vinu Dev <> writes:
> Can u pls help me as 
> 1) Who issues these PTRACE_PEEKTEXT-1.

These are probably the calls to ptrace-target.c:ps_pdread made by
libthread_db.  Try setting a breakpoint there.

> 2) What cause this (why a large quantity of PTRACE_PEEKTEXT-1 issued to
>    target program from rda)

As I said before:

> > 4-5 seconds sounds about right.  If I remember correctly, it's due to
> > libthread_db's need to read huge amounts of memory from the program
> > being debugged each time it stops.

Just to make sure you have the big picture: is not the
thread library.  It is a library that *debuggers* link with to debug
multi-threaded programs.  The idea is that the debugger calls
functions in libthread_db to do things like get the list of all
threads, read a thread's registers, and so on.  libthread_db itself
calls back to functions in the debugger whose names start with 'ps_'
to do the actual reading and writing of memory, and access lightweight
processes' registers.

In theory, this allows the debugger to be ignorant of the details of
the thread library: and are always
distributed as a pair, so as long as is working, the
thread implementation could change without affecting the debugger.

In practice, thread implementations have gotten less complicated than
they used to be, and with NPTL isn't worth the added

      reply	other threads:[~2005-05-16 21:14 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-04-06 10:58 Vinu Dev
2005-04-06 20:06 ` Jim Blandy
2005-04-07  5:01   ` Vinu Dev
2005-04-27  8:47     ` Jim Blandy
     [not found]       ` <>
2005-05-16  4:20         ` Vinu Dev
2005-05-16 21:14           ` Jim Blandy [this message]

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