State of x86_32 port of JEP 425: Virtual Threads (Preview)

[Ron Pressler]

> On 15 Jun 2022, at 17:54, Aleksey Shipilev <shade at redhat.com> wrote:
> 
> Hi,
> 
> Adding to the pile of port reports for Loom.
> 

Hi Aleksey, and thank you for that great work!

> 
> Anyhow, the choice between "ship x86_32 without VM continuations" or "ship x86_32 without C2" is obvious: VM continuations are out. So, barring some debugging miracle, I don't expect x86_32 port to be fully ready for JDK 19.

Am I right to understand that to mean that the x86-32 port does fully implement the virtual threads spec, albeit with the “fake virtual thread” implementation rather than VM continuations?

> 
> In fact, it is not even clear to me if the "shared" code is actually fully architecture-independent, or just happens to work on x86_64 and AArch64. The current code needs to have significant cleanup, refactoring and (re-)documentation for sane porting/debugging work. This, I think, should be #1 priority, and before that is done and ports are able to catch up, it would be unwise to pile more Loom stuff on.
> 

The current implementation focused on x64 and aarch64, and it is certainly possible that some assumptions about those architectures crept in. Over time, I expect that contributions from maintainers of other ports would gradually guide refactoring of the code into a more platform independent shape. Of course, any port maintainer who wishes to join the project and participate more actively is more than welcome.

— Ron