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From: Michael Snyder <msnyder@vmware.com>
To: Dave Korn <dave.korn.cygwin@googlemail.com>
Cc: Jie Zhang <jie.zhang@analog.com>,
	  "gdb@sourceware.org" <gdb@sourceware.org>
Subject: Re: Reset breakpoint after load?
Date: Thu, 21 Jan 2010 18:29:00 -0000	[thread overview]
Message-ID: <4B589CF2.2040304@vmware.com> (raw)
In-Reply-To: <4B582A02.2040501@gmail.com>

Dave Korn wrote:
> On 19/01/2010 07:36, Jie Zhang wrote:
> 
>> gdb-comm.exp sets breakpoints on exit and abort before load. The problem
>> is that GDB tries to skip prologue according to what it reads from
>> memory, which might contain random data since the executable has not
>> been loaded into memory. In my case, sometimes skip_prologue might skip
>> one or two more instructions, which happens to be an exception
>> instruction and will trap the processor into an exception event loop
>> after running the executable before hit the breakpoints.
> 
>   Something is wrong here.  Before the inferior is started, gdb should be
> looking at the prologue bytes from the executable image file, not the inferior
> memory.  Is something going wrong in gdb_comm_file_cmd()?

Dave, Jie,

I don't believe that gdb can tell when the (remote) inferior
is started.  All gdb knows is that target remote is started.
Thus, if we connect to target remote and then load the image,
there is an interval during which gdb will attempt to read
the prologue bytes from un-initialized target memory.

Seems to me, that interval is a bad time to set breakpoints.

Michael


  parent reply	other threads:[~2010-01-21 18:29 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-01-19  7:36 Jie Zhang
2010-01-21 10:01 ` Dave Korn
2010-01-21 12:52   ` Jie Zhang
2010-01-21 18:29   ` Michael Snyder [this message]
2010-01-21 21:20     ` Daniel Jacobowitz
2010-01-21 22:41       ` Jie Zhang
2010-01-22  2:15         ` Paul Koning
2010-01-22  3:05           ` Jie Zhang
2010-01-22 11:46             ` Paul Koning
2010-01-22 13:46               ` Daniel Jacobowitz
2010-01-22 18:19               ` Michael Snyder
2010-01-21 22:35     ` Jie Zhang

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