Project proposal: RISC-V port

[Palmer Dabbelt]

On Fri, 09 Feb 2018 02:57:21 PST (-0800), edward.nevill at gmail.com wrote:
> Hi,
>
> I would like to voice my support for the creation of this project.
>
> The process for creation of a new OpenJDK project is described at http://openjdk.java.net/projects/#new-project
>
> The initial discussion should be sent to the general discussion list, discuss.at.openjdk.dot.java.dot.net. I have cc'd this to the general discussion list.

Thanks.

> Assuming that the group lead of the porters project agrees to sponsor the project then the call for votes should be sent to
> announce.at.openjdk.dot.java.dot.net.
>
> Note that only current OpenJDK contributors may propose the creation of a new project. If you are not a current OpenJDK contributor I am happy to propose the project on your behalf.

We never submitted the Tilera port, so I'm not a contributor at all.  It would 
be great if you could propose the project for me.

> http://openjdk.java.net/bylaws#contributor
>
> I am happy to devote some 'spare' time to this project, but this will me limited to a few hours per week.

Well, that's about all the time I'll have as well :).  I know that OpenJDK is 
way more work than a spare time project, but I'm hoping that we can at least 
get things started with a community effort and then see where things go from 
there.

> I agree with the overall approach you outline below. You will probably end up doing C1 anyway. The s390 port tried to do it without doing C1 and they ended up doing C1.
>
> Andrew Haley's suggestion of using a built in simulator is a good one. This was the approach used on the aarch64 project and it was invaluable  not just in terms of development time in the absence of hardware but in terms of debuggability. Also OpenJDK depends on a huge list of packages to build. Using this approach you can build and run on x86 while all the dependant packages are being ported.

That makes sense.  IIRC there were a lot of headaches involved in getting this 
all together last time, and having a simulator seems like a good idea.

>
> All the best,
> Ed.
>
>
> On Thu, 2018-02-08 at 08:38 -0800, Palmer Dabbelt wrote:
>> [Sorry for the second email, it appears my SiFive email doesn't want to
>> subscribe to porters-dev.]
>>
>> RISC-V is an open standard ISA stewarded by the RISC-V foundation
>> <http://riscv.org>.  With the recent release of glibc 2.27 we now have the full
>> RISC-V software base released from the various upstream repositories, which
>> means it's time to start moving forward with the rest of the software stack.  I
>> ran into Erik at FOSDEM a few days ago and he suggested that we open up the
>> discussion of an OpenJDK port for RISC-V.  While I'm not familiar with the
>> RISC-V Java efforts, I did part of a Hotspot port (a bit of the template
>> interpreter and much of C2) to Tilera's TilePro and TileGx architectures a few
>> years ago so I know a bit about the OpenJDK internals.
>>
>> In the RISC-V community we view Java as a very important missing component of
>> the software ecosystem, so I was thrilled when Erik found me at FOSDMEM and
>> suggested there was community interest in a port.  Unfortunately, I won't have
>> time to properly help out with the port (I'm maintaining Linux, as well as
>> co-maintaining binutils, GCC, and glibc).  That said, I'd be very happy to help
>> out where I can.  I think a good way to move forward might be to:
>>
>> * Create a project to own the RISC-V port, which is what this email is about.
>>   I'm OK being the project lead, at least until we find someone who will have
>> * Clean up our libffi port and submit it upstream.  Stefan O'Rear is in the
>>   process of submitting the port now, so it should all be moving smoothly soon.
>>   Submit patches for our Zero port.  While I didn't do the port I don't mind
>>   cleaning it up and submitting it.  I've added Martin who was more involved
>>   with the original port.  I think he's not working on RISC-V stuff now that
>>   he's at Google, though.
>> * Move forward with a proper OpenJDK port, starting with the template
>>   interpreter and eventually adding C2.  I'm not sure if C1 is actually
>>   deprecated, but we decided not to bother with it at Tilera because it didn't
>>   seem worth the extra effort at the time.  Of course, this would be up to
>>   whomever is actually doing the work :).
>>
>> There appears to be considerable community interest in a RISC-V OpenJDK port,
>> so my hope is that while I don't have time to directly contribute much myself
>> that we'll be able to get something sane up and running.  Interested users can
>> test on QEMU, and we've recently announced a board (and associated beta program
>> that provide free boards to open source developers) so there's some hardware to
>> run on as well.
>>
>> I'd like to request that the Porters Group sponsors this project with me as the
>> lead.
>>
>> Thanks!