Project Proposal: PowerPC/AIX port

[Volker Simonis]

On Tue, May 8, 2012 at 12:56 PM, Alan Bateman <Alan.Bateman at oracle.com> wrote:
> On 07/05/2012 16:03, Simonis, Volker wrote:
>>
>> :
>>
>> 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.
>
> Volker - can you say anymore about the interface between the VM and class
> libraries? In particular, do you envisage that this project will want to
> evolove the existing interface as part of some future push into the main
> line? I may be reading too much into this but I would think that any changes
> would require wider discussion beyond the porting project.
>

The "VM interface" part of the project will be mainly a playground for our
IBM colleagues as they have a natural interest to interface the OpenJDK
class library with their alternative VM implementation. We as SAP are interested
in this topic because it may help us to more easily support old Java releases
with newer VM versions.

We are aware of the  former "Common VM Interface" project
(http://openjdk.java.net/projects/cvmi/) which was started as part of the
OpenJDK Community Innovators' Challenge. But as far as we can see, this
project has been discontinued.

While defining such a new interface is surely not the main purpose of this
project it may very well help to push things into the right direction - perhaps
in the same way as the MacOS X port restarted the discussion about the
refactoring of the native class library code.

> For the linux-ppc port, and based on your experiences porting to this
> target, do you envisage bug fixes, say for memory ordering issues, in many
> areas of the libraries? If there are non-ppc specific
> reliability/portability fixes then maybe they should be examined on a
> case-by-case basis to see whether they should go into jdk8 anyway,
> irrespective of when the ports come up for review to go into the main line.
>

With regards to the linux-ppc port, we don't see many changes in the class
library area - they are mainly in the shared HotSpot code.

But we are of course highly interested in bringing such changes as
fast as possible
into the jdk7/8 main branches. We think that smaller, isolated changes
in shared code
may be integrated from the porting repository into the main line at
any time if this seems
reasonable (i.e. if they don't affect the stability and performance on
the existing platforms
while fixing potential problems or have a positive impact on new platforms).

Regards,
Volker

> -Alan.