Re: break doesn't work with thread on mips

["H . J . Lu" <hjl@lucon.org>]

On Wed, Mar 06, 2002 at 05:26:46PM -0800, Michael Snyder wrote:
> "H . J . Lu" wrote:
> > 
> > On Wed, Mar 06, 2002 at 05:20:34PM -0800, Michael Snyder wrote:
> > > "H . J . Lu" wrote:
> > > >
> > > > When I do
> > > >
> > > > # gdb a.out
> > > > (gdb) b main
> > > > Breakpoint 1 at 0x400910: file x.c, line 25.
> > > > (gdb) r
> > > > (gdb) del 1
> > > > (gdb) b main
> > > > reading register sp (#29): No such process.
> > > >
> > > > That is break no longer works after the program runs if thread is used.
> > > > Why does gdb want to read sp anyway?
> > >
> > > Probably because it has to analyze the prologue of main,
> > > to place the breakpoint after the prologue.  Many prologue
> > > analyzers will poke around at the stack.
> > 
> > Why does gdb do that? The program has stopped.
> 
> You gave it a symbol, "main".  It knows that you don't really want
> to set a breakpoint at the address corresponding to that symbol
> (the label or entry-point of main), but instead you would really
> like to set a breakpoint at the first instruction after the prologue
> of main.  It's not really useful to set a breakpoint before that.
> 
> The fact that you happen to be sitting at that exact address is
> irrelevant -- gdb doesn't know that.

My question is why gdb pokes a dead process. There is nothing to
poke with. FYI, it only happens with thread.


H.J.