Re: [PATCH 05/05] Linux Kernel Markers, non optimized architectures

[Mathieu Desnoyers <mathieu dot desnoyers at polymtl dot ca>]

* Karim Yaghmour (karim.yaghmour@kryptiva.com) wrote:
> ----- KRYPTIVA PACKAGED MESSAGE -----
> PACKAGING TYPE: SIGNED
> 
> Mathieu Desnoyers wrote:
> > The main goal of this config option is for embedded systems which doesn't 
> support live code modification. Maybe we can put that under "embedded 
> sytems" menu ?
> 
> Not sure whether you had had other feedback on this elsewhere in
> the rest of the thread, but yes, this would make sense if the
> "embedded" angle is the only reason we need this (and not, say,
> performance, etc.) Also, having done that, maybe it would make
> some sense to have it be a "disable" rather than "enable":
> CONFIG_MARKERS_DISABLE_OPTIMIZATION?
> 

Hi Karim,

Yes, that was indeed the first way I implemented it, as a "disable"
option. One of the main thing we have to figure out before I modify this
is if we want to have the generic version of markers available in a
"forced" manner at the marker site with the GEN_MARK macro instead of
the MARK macro (this is the actual implementation). It has proven to
be useful to instrument lockdep.c irq enable/disable tracing functions.
The reason why is because they are called just before the trap handler
returns and I need it to do XMC on x86 and x86_64. It would therefore
cause a recursive trap.

I think it makes sense to have this kind of support for hard-to-instrument
sites within the marker infrastructure, but the cost is to have two
marker flavors : MARK and GEN_MARK (but really GEN_MARK is only intended
for a few sites).

Mathieu

> Karim
> 
> 
> ----- KRYPTIVA SIGNED MESSAGE -----
> This email claims to have been packaged by Kryptiva.
> To process this email and authenticate its origin, get
> the free plugin from:
> http://www.kryptiva.com/downloads
> 
> ----- KRYPTIVA SIGNATURE START -----
> AvWVqAAAAAIAAAABAAAAAAAATiACAQAAAAC3AQAIAAAAAgAAAAECABTXxT4xHdR4/1uU1hL2
> +TaPrqNB0wMAFNa8GHXZWJH5Dz+D76vfh6JhvWLvBAAUpuIZcCAkCC+ldyaBuoAWxK50HiQF
> ABRI38gc/foDHQsS6X3W0VP4xTukBwYAFDzvzh+u6zVtolglAZrnE7FOmtZDBwAUTxyTas6N
> WLapdnSnAwVHeC06/ioRABgAAAAAAABOIEXWD8AACTdnAAAAAAAAAN8TAAQAAAAAAAAAggP+
> K8Gk1SWj+c67jiJerodkr1gntoa9dJVVN6InxB824CfKC6flE4JMWtffw0Dxh0cJ8iOQ8UeC
> zoWzTs9Z+K9j1CL11CHkIIit3RK3hnfnby6whr4xoZ9UX/BUUv8FVKZeyRg7SbDKlhEZTwIH
> 7axjVQJ6MGU7h+0/5dKCDMEtzPY=
> ----- KRYPTIVA SIGNATURE END -----

-- 
Mathieu Desnoyers
Computer Engineering Ph.D. Candidate, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68