Re: [PATCH] 2.4.0 i386 watchpoint problems

From: Linus Torvalds (torvalds@transmeta.com)
Date: Fri Sep 22 2000 - 13:25:21 EST


On Fri, 22 Sep 2000, Andi Kleen wrote:
> >
> > No. The current process is always the same one we send the signal to, so
> > that test ends up being irrelevant.
>
> Really ? I thought the original user wanted the signal to be sent to the
> debugger (e.g. the idle process probably couldn't care less about hardware
> breakpoints even when they hit in an interrupt handler which it is running)

They get sent to the original process.

The debugger then catches the actual signal handler event, see
arch/i386/kernel/signal.c.

Remember: debug traps work even without debuggers. You can use a "int 3"
in your program if you want to have self-debug somewhere. Not many people
do it, of course, but there's nothing fundamentally wrong in just catching
SIGTRAP yourself, and doing something special on debug events.

                        Linus

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