Subject: Re: linux-next: add utrace tree

From: Ingo Molnar <[email-masked]>
Date: Fri, 29 Jan 2010 10:11:16 +0100

* Ananth N Mavinakayanahalli <[email-masked]> 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.

	Ingo