Re: regarding transparent data ranges (in tracepoint support)

[Daniel Jacobowitz <drow@mvista.com>]

On Wed, Nov 19, 2003 at 02:50:29PM -0500, Newman, Mark (N-Superior Technical Resource Inc) wrote:
> Sorry about the tunnel vision.  When the SUT exits we loose all of the
> tracepoint data in target memory. Stopping that from happening is the
> next thing on my list after I finish making interrupt work.  After the
> program finishes it should not exit without an ok from the engineer.
> 
> So Ankit if that is what you are looking to do I agree completely.
> However can't gdbserver do something more like the restart that occurs
> with a "w" or "x" status after the putpkt in the case statement in
> server.c

For recent Linux kernels see PTRACE_EVENT_EXIT.

In general, however, there's no easy way to prevent it from exiting
without that.

> 
>                                            Mark
> 
> > -----Original Message-----
> > From: Daniel Jacobowitz [mailto:drow@mvista.com]
> > Sent: Wednesday, November 19, 2003 2:39 PM
> > To: Newman, Mark (N-Superior Technical Resource Inc)
> > Cc: ankit thukral; Jim Blandy; gdb@sources.redhat.com
> > Subject: Re: regarding transparent data ranges (in tracepoint support)
> > 
> > 
> > On Wed, Nov 19, 2003 at 02:34:49PM -0500, Newman, Mark 
> > (N-Superior Technical Resource Inc) wrote:
> > > Guys - again please excuse my ignorance but
> > > 
> > > I was assuming that transparent memory would either be
> > > 
> > > In ROM
> > > In a write protected page
> > > In an unprotected page (for those systems without memory protection)
> > > Possibly swapped out to the disk (for those system with a disk)
> > > 
> > > However definitely readable by "read_inferior_memory".
> > > 
> > > Why would the data not be loaded into some form of memory?  
> > > What kind of data are we talking about?
> > 
> > Ankit is talking about reading the transparant tracepoint data after
> > the program has exited - when its memory isn't there any more.
> > 
> > > 
> > >                              Mark Newman
> > > 
> > > > -----Original Message-----
> > > > From: gdb-owner@sources.redhat.com
> > > > [mailto:gdb-owner@sources.redhat.com]On Behalf Of Daniel 
> > Jacobowitz
> > > > Sent: Wednesday, November 19, 2003 1:56 PM
> > > > To: ankit thukral
> > > > Cc: Jim Blandy; gdb@sources.redhat.com
> > > > Subject: Re: regarding transparent data ranges (in 
> > tracepoint support)
> > > > 
> > > > 
> > > > On Wed, Nov 19, 2003 at 08:25:37AM -0800, ankit thukral wrote:
> > > > > 
> > > > > --- Jim Blandy <jimb@redhat.com> wrote:
> > > > > > 
> > > > > > ankit thukral <ankit_plug@yahoo.com> writes:
> > > > > > 
> > > > > > > hi all,
> > > > > > >      i read about the transparent data ranges and
> > > > > > > learned that data in these ranges are not supposed
> > > > > > to
> > > > > > > be collected by the remote stub since they belong
> > > > > > to
> > > > > > > read-only segment of the debuggee.my problem is :
> > > > > > a
> > > > > > > TSTART would start the debuggee and it may so
> > > > > > happen
> > > > > > > that the debuggee finishes executing.at this
> > > > > > point,if
> > > > > > > the GDB requests for some data in the transparent
> > > > > > data
> > > > > > > range,then how can the remote stub provide it with
> > > > > > one
> > > > > > > since the debuggee has exited ?
> > > > > > 
> > > > > > If the target is a gdbserver, then it would need to
> > > > > > read the bytes
> > > > > > from the executable file.  This is easy to do with
> > > > > > BFD, but if I
> > > > > > remember right, gdbserver doesn't use BFD at the
> > > > > > moment; not sure how
> > > > > > to get around that.
> > > > > > 
> > > > > > If the target is an embedded system, then presumably
> > > > > > the transparent
> > > > > > data ranges correspond to ROM regions, so the data
> > > > > > is still there.
> > > > > 
> > > > > 
> > > > > 
> > > > >   how about setting a (internal) breakpoint in the
> > > > > debuggee which would prevent it from exiting even
> > > > > though it has finished executing main(),and then
> > > > > entertain GDB requests for the transparent (or
> > > > > read-only) memory regions by reading from the memory
> > > > > of the debuggee???
> > > > 
> > > > That would work (but be wasteful).  At least on Linux, 
> > you could read
> > > > /proc/pid/maps to find what ranges correspond to where in 
> > what file,
> > > > and save that information.
> > > > 
> > > > -- 
> > > > Daniel Jacobowitz
> > > > MontaVista Software                         Debian 
> > GNU/Linux Developer
> > > > 
> > > 
> > 
> > -- 
> > Daniel Jacobowitz
> > MontaVista Software                         Debian GNU/Linux Developer
> > 
> 

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer