Project proposal: RISC-V port

[Christian Thalinger]

> On Feb 9, 2018, at 6:08 AM, Andrew Dinn <adinn at redhat.com> wrote:
> 
> On 09/02/18 10:57, Edward Nevill wrote:
>> I would like to voice my support for the creation of this project.
> 
> Ditto!
> 
>> I am happy to devote some 'spare' time to this project, but this will
>> me limited to a few hours per week.
> 
> I wish I could make a similar offer but unfortunately I cannot make that
> commitment at present.
> 
>> 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.
> 
> I'd second that view. Also, C1 is more valuable than it appears e.g. it
> is still very valuable as a companion to Graal when the latter replaces
> C2 via JVMCI.

…or don’t do C2 or C1 at all and just do Graal and use AOT :-)

Everything else is a waste of time, in my very biased opinion.

> 
>> 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.
> 
> I agree. This was an enormous boost to productivity when doing the
> AArch64 port and I would recommend it to anyone doing a port --
> especially while early chips still run the risk of hardware bugs.
> 
> Andrew Haley and I did document this process, albeit only in overview,
> in our FOSDEM talk from 2013. I'd be happy to help anyone wishing to
> attempt the same trick understand in more detail how we did it -- in
> particular how we implemented debug support in the simulator (of course,
> the AArch64 sim code, including debugger is still available on
> sourceforge and the jdk code which used it is still in the AArch64 port
> repo).
> 
> regards,
> 
> 
> Andrew Dinn
> -----------
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