Project Proposal: PowerPC/AIX port

Simonis, Volker volker.simonis at sap.com
Mon May 7 08:03:48 PDT 2012


In accordance with the OpenJDK guidelines [1], I'd like to start the
discussion of a new project to port the OpenJDK to the PowerPC/Linux
and PowerPC/AIX platforms.
 
The goal of the project will be to provide full-featured and certifiable
version of the OpenJDK on the two platforms which can be ultimately integrated
into the main OpenJDK development branch.
 
Besides the very fact that this project will enrich the OpenJDK platform
coverage with two new platforms we see two more main benefits. By supporting
the PowerPC architecture we will add the first weak memory architecture to the
OpenJDK. As we already know from past experience, this will unveil all kinds
of intricate memory ordering problems. Moreover, adding AIX as a new Unix
flavor to the set of supported operating systems will uncover numerous
implicit assumptions and shortcuts inside the code base which only hold true
for Linux and Solaris. We strongly believe that fixing these issues will
considerably increase the robustness and further portability of the OpenJDK.

The technical approach and a brief project agenda are as follows:
- provide an interpreter-only version of HotSpot based on the 
  CPP interpreter on Linux/PPC64
- provide a full set of tools and class libraries for AIX and
  Linux on PPC32/64
- provide a complete certifiable JDK 7 on Linux/PPC64
- provide a complete certifiable JDK 7 on AIX/PPC64
- provide an implementation of the C2 server compiler on both 
  AIX/PPC64 and Linux/PPC64
- integrate the new ports upstream into the main JDK8/9 branches

To assist with project bootstrapping and maintain momentum of VM porting issues
independently from class library issues the project will evolve an interface
between the VM and class libraries that allows alternative implementations
to be substituted.  The project will start by porting the stable JDK 7 codebase
with a view to moving onto the JDK 8 stream as soon as practical.
 
The project will have one, complete OpenJDK forest which will be initially
cloned from the current jdk7u forest as well as a project mailing list and web
site. We plan to start the project without a formal review process but this may
change by the time the port gets more mature.
 
The project will initially be driven jointly by IBM and SAP who both have a
long-standing experience in developing and porting JDKs to various platforms
including Linux/PowerPC and AIX/PowerPC. But as this is an open source project
of course anybody interested is highly welcome to join the porting effort. The
complete development process and discussions will happen in the open on the
project mailing list.
 
I volunteer as an initial project lead of this porting project and as such I
would like to propose the following initial committers: Steve Poole (IBM), Neil
Richards (IBM), Götz Lindenmaier (SAP) and Volker Simonis (SAP).
 
We kindly ask the Porters group to become the sponsor of this project.

With best regards,
Volker

[1] http://openjdk.java.net/projects/#new-project



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