From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from issun5.hti.com ([130.210.202.3]) by issun6.hti.com (Netscape Messaging Server 3.6) with ESMTP id AAA6C60 for ; Tue, 1 May 2001 11:36:04 -0500 Message-ID: <3AEEEC48.80709@link.com> Date: Tue, 01 May 2001 13:03:04 -0400 From: "Richard F Weber" MIME-Version: 1.0 Subject: Re: About reading /proc/*/mem References: Content-Type: multipart/alternative; boundary="------------090203020208030401040307" Sender: owner-linux-mm@kvack.org Return-Path: To: Alexander Viro Cc: "Eric W. Biederman" , linux-mm@kvack.org List-ID: --------------090203020208030401040307 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit The main thing I'm looking to do is examine data that's part of a real-time process. The process's execution can't be interrupted, otherwise it makes debugging it inaccurate. The applications is certainly not looking to see every line of code get executed, but rather have a real-time monitor of a symbol as it gets modified. Now viewing/selecting the symbol is done through a combination of nm's & a console based util (hopefully GTK Based in the future). Other applications include recording this data to disk for later playback & analysis. Now the next logical step would be to create a debug module in the RT system itself that dumps out the values we care about. The problem with this is we are looking at a lot of legacy code (done in fortran, C & Ada) as well as tons of variables. By peeking at the memory on the fly we can dynamically decide which values are important for this run, without having to record all possible data to the disk (which in itself would be quite painful since disk accesses would make debugging again difficult). Granted, it's probobally not a very popular application, but it's still one which is present in many of the Big Unixes, and so far has me stumped as to how to get it working correctly under Linux. --Rich Alexander Viro wrote: >On 1 May 2001, Eric W. Biederman wrote: > >>>Unfortunately, ptrace() probobally isn't going to allow me to do that. >>>So my next question is does opening /proc/*/mem force the child process >>>to stop on every interrupt (just like ptrace?) >>> >> >>The not stopping the child should be the major difference between >>/proc/*/mem and ptrace. >> > >Could somebody tell me what would one do with data read from memory >of process that is currently running? > >-- >To unsubscribe, send a message with 'unsubscribe linux-mm' in >the body to majordomo@kvack.org. For more info on Linux MM, >see: http://www.linux.eu.org/Linux-MM/ > --------------090203020208030401040307 Content-Type: text/html; charset=us-ascii Content-Transfer-Encoding: 7bit The main thing I'm looking to do is examine data that's part of a real-time process. The process's execution can't be interrupted, otherwise it makes debugging it inaccurate. The applications is certainly not looking to see every line of code get executed, but rather have a real-time monitor of a symbol as it gets modified. Now viewing/selecting the symbol is done through a combination of nm's & a console based util (hopefully GTK Based in the future). Other applications include recording this data to disk for later playback & analysis.

Now the next logical step would be to create a debug module in the RT system itself that dumps out the values we care about. The problem with this is we are looking at a lot of legacy code (done in fortran, C & Ada) as well as tons of variables. By peeking at the memory on the fly we can dynamically decide which values are important for this run, without having to record all possible data to the disk (which in itself would be quite painful since disk accesses would make debugging again difficult).

Granted, it's probobally not a very popular application, but it's still one which is present in many of the Big Unixes, and so far has me stumped as to how to get it working correctly under Linux.

--Rich

Alexander Viro wrote:

On 1 May 2001, Eric W. Biederman wrote:

Unfortunately, ptrace() probobally isn't going to allow me to do that.  
So my next question is does opening /proc/*/mem force the child process 
to stop on every interrupt (just like ptrace?)


The not stopping the child should be the major difference between
/proc/*/mem and ptrace.


Could somebody tell me what would one do with data read from memory
of process that is currently running?

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux.eu.org/Linux-MM/

--------------090203020208030401040307-- -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux.eu.org/Linux-MM/