<br><tt><font size=2>bobc@us.ibm.com wrote on 02/08/2008 02:41:40 PM:</font></tt>
<br><tt><font size=2><br>
>We all realize there are issues with MPI_Aint's in 32 bit implementations.
</font></tt>
<br><tt><font size=2>>Using signed 32 bit addresses along with 64 bit
offsets can result in </font></tt>
<br><tt><font size=2>>some pretty broken code. I've reproduced
several problems on </font></tt>
<br><tt><font size=2>>BGL/BGP/linux. The problems are most obvious
with romio files > 2G or </font></tt>
<br><tt><font size=2>>virtual addresses > 2G.</font></tt>
<br><tt><font size=2><br>
Earlier this month I posted some comments to this mailing list about </font></tt>
<br><tt><font size=2>32-bit MPICH/ROMIO/MPI_Aint issues (see above and
the archive). </font></tt>
<br>
<br><tt><font size=2>We've started to work on the problem. We're
(optionally) making </font></tt>
<br><tt><font size=2>MPI_Aint a 64 bit signed value even when integers/pointers
are 32 bit </font></tt>
<br><tt><font size=2>values.</font></tt>
<br><tt><font size=2><br>
We'd like to start sending fix patches to the community for comment.</font></tt>
<br><tt><font size=2><br>
However, since we are (in parallel) contributing our BGP code back</font></tt>
<br><tt><font size=2>to MPICH and trying to converge on a common code base
of 1.0.7,</font></tt>
<br><tt><font size=2>and because this problem applies to any 32-bit platform,</font></tt>
<br><tt><font size=2>we thought we should move the discussion to mpich-discuss
to get</font></tt>
<br><tt><font size=2>the larger community's comments. </font></tt>
<br><tt><font size=2><br>
It's unlikely, at this point, that our patches would apply to MPICH2,</font></tt>
<br><tt><font size=2>but that is our goal after the 1.0.7/BGP patch settles.
For now, we'd</font></tt>
<br><tt><font size=2>be sending these as RFC (request for comment) patches.</font></tt>
<br><tt><font size=2><br>
Please let us know if you agree with discussing this on mpich-discuss,</font></tt>
<br><tt><font size=2>or if there is a better place.</font></tt>
<br><tt><font size=2><br>
Bob Cernohous: (T/L 553) 507-253-6093<br>
<br>
BobC@us.ibm.com<br>
IBM Rochester, Building 030-2(C335), Department 61L<br>
3605 Hwy 52 North, Rochester, MN 55901-7829<br>
<br>
> Chaos reigns within.<br>
> Reflect, repent, and reboot.<br>
> Order shall return.<br>
</font></tt>