Date: Fri, 24 Nov 1995 11:04:51 +0100 (MET) From: grog@lemis.de (Greg Lehey) To: gavin@linux1.dlsu.edu.ph (Gavin Chan Lim) Subject: Re: ptrace() Message-ID: <199511241005.LAA24697@allegro.lemis.de> In-Reply-To: <Pine.LNX.3.91.951123133345.1208B-100000@ccslinux.dlsu.edu.ph> from "Gavin Chan Lim" at Nov 23, 95 01:36:09 pm
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Gavin Chan Lim writes:
> I've found the source codes for GDB. I have certain questions regarding
> ptrace(). I hope you can answer them.
>
> 1. What does "Attach/Detach to the process" mean? (PT_ATTACH, PT_DETACH)>
> 2. Does request PT_READ_I mean read the text segment?
Yes, On the PDP-11. On the i386, it means read the process address
space.
> 3. Does request PT_READ_D mean read the data segment?
Yes, On the PDP-11. On the i386, it means read the process address
space. You'll notice that Linux has done away with the difference
between these two, which are redundant, but this is UNIX :-)
> 4. What's the last argument (int data) of ptrace() for?
It's used to pass data where necessary:
PT_CONTINUE - specify a signal number to be sent to the child
process before it continues. 0 means don't send a
signal.
PT_WRITE_U - data to be written to the user area
PT_WRITE_I - data to be written to the process data space
PT_WRITE_D - data to be written to the process data space
Greg
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