Re: [patch 00/11] Hardware Breakpoint interfaces

Ingo Molnar
2009-03-11T17:31:31Z

* K.Prasad <prasad@linux.vnet.ibm.com> wrote:

> On Wed, Mar 11, 2009 at 12:34:43PM -0400, Alan Stern wrote:
> > On Wed, 11 Mar 2009, K.Prasad wrote:
> >
> > > The hardware breakpoint interfaces haven't been put under any CONFIG_
> > > till now, but I think we should bring them under a new config, say
> > > CONFIG_HW_BREAKPOINT. It would help create a dependancy for
> > > CONFIG_KSYM_TRACER too.
> >
> > With these patches, ptrace is dependent on hw-breakpoint.
> > You can't disable CONFIG_HW_BREAKPOINT without breaking
> > ptrace.
> >
> > Alan Stern
> >
>
> Agreed. We might have to retain the old code for ptrace and
> put the new implementation under #ifdef CONFIG_HW_BREAKPOINT
> to get them working. What do you think?

With the simple reservation mechanism i suggested i have no
problem with having HW_BREAKPOINT enabled [selected]
unconditionally on x86.

Your ptrace changes are an improvement in terms of code quality
so as long as the facility is simple and obvious, it's a step
forward.

#ifdefs are ugly and hard to maintain - especially in such a
rarely used and still critical API as ptrace.

Ingo