[Qemu-devel] Problem with threads in Scratchbox with Qemu for ARM

[Qemu-devel] Problem with threads in Scratchbox with Qemu for ARM

[Stephane Epardaud]

Hello,

I'm trying the Scratchbox/Maemo devkit for the Nokia770/N800 ARM device, and I'm 
having a problem running a multi-threaded program under application Qemu ARM 
emulation on my x86 linux box.
The application I'm trying to run is the Boehm GC, which seems to run fine on 
the N770 device, but fails to work on that scratchbox/qemu ARM emulation.
The application is available here:
http://www.hpl.hp.com/personal/Hans_Boehm/gc/gc_source/gc7.0alpha7.tar.gz
In order to make it work on scratchbox/maemo you have to change the line 1729 of 
include/private/gcconfig.h from:
#       define LINUX_STACKBOTTOM
to:
#       define HEURISTIC2

For a real ARM the original file should work.

To reproduce the problem:
./configure
make
make gctest
./gctest

This deadlocks and strace hints that signals sent by pthreads are delivered to 
the wrong threads. We've discussed this already on the GC mailing list there:
http://article.gmane.org/gmane.comp.programming.garbage-collection.boehmgc/1556

Does anyone know of known problems under Qemu for ARM and pthreads ?
Or any way I could verify that it's really Qemu's fault ?
Thanks.

Re: [Qemu-devel] Problem with threads in Scratchbox with Qemu for ARM

[Vincent Palatin]

> Does anyone know of known problems under Qemu for ARM and pthreads ?

Yes, it is known ... last occurence in the mailing list archive  is :

On Saturday 20 January 2007 14:43, Paul Brook wrote:
[...]
>
> Threaded applications don't work reliably under qemu.
> See mailing list archives for discussions of the technical reasons why.
>
> Paul

-- 
Vincent

Re: [Qemu-devel] Problem with threads in Scratchbox with Qemu for ARM

[Stephane Epardaud]

Vincent Palatin wrote:
>> Does anyone know of known problems under Qemu for ARM and pthreads ?
> 
> Yes, it is known ... last occurence in the mailing list archive  is :

Thanks, I guess I failed to find the exact posts mentioning the reasons.
Any idea if this area will improve in the near future ? Or if there is a good 
reason why it will not improve ?

Re: [Qemu-devel] Problem with threads in Scratchbox with Qemu for ARM

[Vincent Palatin]

On Friday 02 February 2007 16:11, Stephane Epardaud wrote:
> Vincent Palatin wrote:
> >> Does anyone know of known problems under Qemu for ARM and pthreads ?
> >
> > Yes, it is known ... last occurence in the mailing list archive  is :
>
> Thanks, I guess I failed to find the exact posts mentioning the reasons.
> Any idea if this area will improve in the near future ? Or if there is a
> good reason why it will not improve ?

I think some useful information on this topic are in the thread "[PATCH]ish 
NPTL support." on qemu-devel list.

The thread starts at this message :
http://lists.gnu.org/archive/html/qemu-devel/2006-12/msg00079.html
the following message gives interesting ideas :
http://lists.gnu.org/archive/html/qemu-devel/2006-12/msg00208.html
( portability issue on host without modern NPTL)

Another big issue is that dynamic translator is not thread safe, see Fabrice 
post :
http://lists.gnu.org/archive/html/qemu-devel/2006-12/msg00163.html

-- 
Vincent

Re: [Qemu-devel] Problem with threads in Scratchbox with Qemu for ARM

[Stephane Epardaud]

Thanks for the infos!