What next for aarch32

[Simon Nash]

Edward Nevill wrote:
> [crossposted to aarch64 because of relevance there as well]
> 
> Hi,
> 
> So, having gone from a situation 18 months ago where the only port
> available in OpenJDK for aarch32 was the Zero port, we now find
> ourselves with an embarrassment of riches.
> 
> - The template interpreter port contributed by Linaro
> - The C1 port contributed by Azul
> - The C1/C2 port contributed by Oracle
> - We also have in the aarch32 port area, the Oracle C1/C2 port for
> aarch64 as it is integrally bound with the aarch32 port.
> 
> To this end I declare the aarch32 project a great success and would
> like to thank all those who have contributed to the project.
> 
> However, it does leave the question of what to do next.
> 
> My 30,000ft view is
> 
> - jdk8u aarch32
> 
> We should use the existing Azul port. I see no enthusiasim for
> backporting the Oracle C1/C2 port from jdk9 to jdk8u.
> 
> - jdk9 aarch32
> 
> We should use the Oracle port. Again I see no enthusiasm for forward
> porting the C1 port from jdk8u to jdk9 and even if it were forward
> ported it would still lack C2.
> 
> - jdk8u aarch64
> 
> Will continue to be supported as is by the aarch64 project
> 
> - jdk9 aarch64
> 
> We should use the existing port that has been developed as part of the
> OpenJDK process. It is the incumbant port and is used in
> Redhat/Ubuntu/Debian. It has been evaluated, tested and benchmarked by
> ARMs silicon partners and has also been evaluated by very large
> partners for use in large scale server applications. We cannot simply
> change the existing OpenJDK jdk9 aarch64 implementation without very
> good reason.
> 
> I am perfectly open to having the Oracle jdk9 port in the mainstream. I
> understand how it is integrally bound with the aarch32 port and it
> would be difficult and unnecessary to separate out the aarch32 port on
> its own for inclusion in jdk9. I think the --with-abi-
> profile=arm/aarch64 is acceptable even if it is not very pretty. I find
> the naming of the option "--with-abi-profile=xxx" fairly meanless and
> would prefer the more direct "--with-port=xxx".
> 
> Note that none of this is based on any technical merit of one port over
> another in terms of code quality, testing, benchmarking etc. It is
> simply preserving the status quo.
> 
> I think it will be difficult to get the aarch32 port into jdk9 because
> of the timescales. JDK 9 is now FC so no new features are accepted
> without an exception being raised. I am happy to try submitting a JEP
> to get it included, but I doubt it will be successful.
> 
> Our experience with the aarch64 port has taught us that it takes a lot
> longer than expected to merge a new port into the mainstream. I believe
> the process took about 6 months (Andew Haley may correct me on this).
> 
> Firstly we will need a sponsor within Oracle for the aarch32 port
> (Vladimer Koslov was the sponsor for the aarch32 port). Then the port
> will need to be merged to a 'staging' port so that it can be tested
> with Oracle's JPRT / Oracle's other internal tests. Finally it can be
> merged into the mainsteam.
> 
> This was the process followed for the aarch64 port. It may be possible
> to shorten some of this process as the code base is a well known
> quantity (at least within Oracle).
> 
> I think the best way forward with this is to have a discussion with the
> JDK 9 lead, Mark Reinhold, before firing off any JEPs etc.
> 
> We also need to have a discussion of interested parties within
> aarch32/aarch64 communities. I would prefer that as much of that
> discussion takes place in the open, either on the mailing list or in
> open conference calls although I appreciate there may be a need for
> private communications where commercial interests are involved.
> 
> I propose that we resurrect the 'fireside' chats which we had earlier
> in the year on the aarch64 project. These were held on every second
> Thursday at 15:00 UTC, so I would propose restarting these on Thurs
> 20th Oct.
> 
> Unfortunately, I do not have the facility to host these any longer.
> Stuart Monteith from Linaro was hosting these for a while. Stuart:
> Would you be able to host this. Alternatively, could someone else
> volunteer to host this?
> 
> All the best,
> Ed
> 
> 
Dear Ed,
Thanks for all your work on this.  These are exciting times!

I hope very much that it will be possible to get the aarch32 port into
JDK 9.  As  a newcomer to OpenJDK, I am not sure what is acceptable
after the "feature complete" date but I would hope that adding a new
port target might be more acceptable than adding or changing
functionality in the language or class libraries.

I am willing to help if there is something that I can do.  I am new
to OpenJDK but I have past experience of Java development and
open-source projects.

I can't make the fireside chat on 20th October but I should be able to
join the subsequent chats.

Best regards,
Simon