Re: systemtap ARM port status

[Quentin Barnes <qbarnes at urbana dot css dot mot dot com>]

> Hi Quentin/all,
>
> After a quick look on the systemtap archives, I saw some references to
> an ongoing systemtap ARM port, e.g. [1]. We have some interest on such
> port, but we don't want to dupplicate work. So I have some questions:
>
> - Is there any patches available we could test? We have some OMAP
> boards available so we do some test on them.

Recently I've given a patch to support ARM in the Systemtap runtime
to Martin Hunt.  He's doing a careful review of it for me.  The
patch isn't completely there yet, but it is very, very close to
being complete.  If the ARM port work doesn't make it into the next
weekly snapshot, I'll see about a more direct access.

In the last few days I have found a couple of additional changes to
the ARM patch I sent Martin.  I'm probably going to send them to
him later today. I also am having trouble understanding a couple of
things in the runtime that's causing me trouble.  I wrote them up
and asked him about them.  I think once those things are resolved,
the ARM port of the runtime will be basically 100% there.

Note though that the ARM port work doesn't yet include all the
changes to get the testsuite to run on an ARM platform.  I'm still
working on those and will be submitting them to the list soon.

> - How are you running the stap scripts on the platform? We are doing
> something like:
>
> 1) On host: stap -p 4 -k script.stap
> 2) Copy generated .ko to target
> 3) On target: insmod stap-module.ko

Well, for now I'm running completely native.  Yes, that's very, very
painful to run gcc and g++ on such a board with an NFS mounted file
system and NFS mounted swap file over loopback.  It can take four
hours of wall time to compile and link the "stap" binary and the
better part of a day to run the full testsuite.

I've had so many problems to solve getting Systemtap to support
ARM, I didn't want to have to also deal with problems introduced
from trying to get it to also support cross-builds simultaneously.
I decided to work on one problem at a time.

There is another group who's adding cross-target support to Systemtap:
http://tree.celinuxforum.org/CelfPubWiki/ELC2007TechnicalShowcase?action=AttachFile&do=get&target=SystemTap_Poster.ppt

I have had only limited contact with them so far.  I would like to
have more and come up to speed on their work.


To back up a bit, where are you getting the ARM Kprobes port from?
Is this based on Sagar and my work I posted to the ARM Linux kernel
mailing list recently, or some other ARM Kprobes port?

> [1] http://sourceware.org/ml/systemtap/2007-q2/msg00231.html
>
> Regards,
> --
> Anderson Lizardo
> Open Source Mobile Research Center - OSMRC
> Nokia Institute of Technology - INdT
> Manaus - Brazil

Quentin