Re: regarding transparent data ranges (in tracepoint support)

[Daniel Jacobowitz <drow@mvista.com>]

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