From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gdb-return-35291-listarch-gdb=sources.redhat.com@sourceware.org>
Received: (qmail 22853 invoked by alias); 20 Aug 2009 01:50:18 -0000
Received: (qmail 22844 invoked by uid 22791); 20 Aug 2009 01:50:18 -0000
X-SWARE-Spam-Status: No, hits=-2.1 required=5.0 	tests=AWL,BAYES_00,SPF_PASS
X-Spam-Check-By: sourceware.org
Received: from qw-out-1920.google.com (HELO qw-out-1920.google.com) (74.125.92.144)     by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Thu, 20 Aug 2009 01:50:10 +0000
Received: by qw-out-1920.google.com with SMTP id 5so2695521qwf.24         for <gdb@sourceware.org>; Wed, 19 Aug 2009 18:50:08 -0700 (PDT)
Received: by 10.224.82.149 with SMTP id b21mr7033355qal.323.1250733007939;         Wed, 19 Aug 2009 18:50:07 -0700 (PDT)
Received: from dyn-209-2-225-148.dyn.columbia.edu (dyn-209-2-225-148.dyn.columbia.edu [209.2.225.148])         by mx.google.com with ESMTPS id 8sm973777qwj.56.2009.08.19.18.50.06         (version=TLSv1/SSLv3 cipher=RC4-MD5);         Wed, 19 Aug 2009 18:50:07 -0700 (PDT)
Cc: gdb@sourceware.org
Message-Id: <187FEE7D-02A2-45C5-8B19-9BB7C6AC984D@gmail.com>
From: kceiwH <kceiwh@gmail.com>
To: Andreas Schwab <schwab@linux-m68k.org>
In-Reply-To: <m2hbw33406.fsf@igel.home>
Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes
Content-Transfer-Encoding: 7bit
Mime-Version: 1.0 (Apple Message framework v936)
Subject: Re: How GDB knows a breakpoint is hit?
Date: Thu, 20 Aug 2009 02:21:00 -0000
References: <84D22DD1-F4AD-4985-A0EC-AF3B53774D10@gmail.com> <m2hbw33406.fsf@igel.home>
X-IsSubscribed: yes
Mailing-List: contact gdb-help@sourceware.org; run by ezmlm
Precedence: bulk
List-Id: <gdb.sourceware.org>
List-Subscribe: <mailto:gdb-subscribe@sourceware.org>
List-Archive: <http://sourceware.org/ml/gdb/>
List-Post: <mailto:gdb@sourceware.org>
List-Help: <mailto:gdb-help@sourceware.org>, <http://sourceware.org/ml/#faqs>
Sender: gdb-owner@sourceware.org
X-SW-Source: 2009-08/txt/msg00190.txt.bz2

Thanks very much.

Mao

On Aug 19, 2009, at 5:09 PM, Andreas Schwab wrote:

> kceiwH <kceiwh@gmail.com> writes:
>
>> I wonder how GDB knows it should stop the inferior when a  
>> breakpoint is
>> hit. I try to read the code but only to find how GDB creates a
>> breakpoint. I thought GDB might change some instructions of  
>> inferior  so
>> that when the inferior executes the modified instructions, GDB   
>> should
>> know. But what the function "create_breakpoint" does is to add  a
>> breakpoint to the list "breakpoint_chain".
>
> Breakpoints are only inserted immediately before the inferior is
> resumed, see insert_breakpoints.
>
> Andreas.
>
> -- 
> Andreas Schwab, schwab@linux-m68k.org
> GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276  
> 4ED5
> "And now for something completely different."