Re: linux-next: add utrace tree

From: Ingo Molnar
Date: Fri Jan 29 2010 - 04:11:45 EST

* Ananth N Mavinakayanahalli <ananth@xxxxxxxxxx> wrote:

> On Fri, Jan 29, 2010 at 08:39:07AM +0100, Ingo Molnar wrote:
> ...
> > When we merged kprobes ~10 years ago we made the (rather bad) mistake of
> > merging a raw, opaque facility and leaving 'the rest' up to some other entity.
> > IBM kprobes hackers vanished the day the original kprobes code went upstream
> > and the high level entity never truly materialized in-kernel, for nearly a
> > decade!
> I don't know what you are referring to here... Kprobes was merged in 2.6.9
> (~August 2004 -- less than 6 years ago). [...]

Ok, 6 years then :-)

> [...] Since then, we did work on ports to powerpc and s390. We implemented
> kretprobes. We made it much scalable using RCU; we did the powerpc booster
> to skip single-step when possible, not to mention various bug fixes over the
> years.

Except it had no real in-kernel user.

> Yes, we did not do the perf integration, but perf did not exist then,
> either.
> Its simply wrong to say people 'vanished'.

It has certainly was a bit stale for years - and with no real users that's
certainly not a surprise. That has changed recently so i'm not complaining. We
just dont want to repeat the same mistake with uprobes.

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