Re: Tracepoint support in Cygnus GDB ?

Eli Zaretskii
2003-09-24T18:12:55Z

> Date: Wed, 24 Sep 2003 16:09:49 +0530
> From: Saravanan <pes@india.hp.com>
>
> 1. Why does GDB not provide this support for local
> host ?

Simple: because no one wrote tracepoints support for native debugging.

> 2. Is it not the case that the features (supposed to
> be) provided by tracepoints can be done using
> breakpoint features only (for instance , we can
> specify COMMANDS for a breakpoint just as we can
> specify ACTIONS for tracepoints) ?

Yes. But tracepoints are supposed to be much more lightweight
(because only raw data is accumulated during the program's run, while
complicated and expensive computations like evaluation of arbitrary
expressions, are left for later). So, theoretically, if tracepoints
were available for native debugging, one could perhaps debug programs
without disrupting their time scale too much, maybe even debug
real-time programs (well, one's allowed to dream once in a while,
right? ;-).

> 3. Does tracepoint use the same TRAP (or ILLEGAL )
> instruction mechanism for tracepoints as it does for
> breakpoints?

IIRC, yes.