RFR: 8273797: Stop impersonating "server" VM in all VM variants

[Magnus Ihse Bursie]

On Wed, 15 Sep 2021 10:02:19 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> As the follow-up for Zero-specific JDK-8273494, we might want to clean up build system logic for all VM variants: stop impersonating "server" VMs for all of them. This basically leaves "core" and "custom" variants to be handled with this patch.
> 
> Additional testing:
>  - [x] Linux x86_64 `core` build passes, `libjvm.so` now in `core`, `jvm.cfg` mentions `-core KNOWN`
>  - [x] Linux x86_64 `custom` (+serialgc,+compiler2) build passes, `libjvm.so` now in `custom`, `jvm.cfg` mentions `-custom KNOWN`

As for eliminating multi-JVM builds: yes, that is on my agenda, but as long as I'm still just working part-time it's hard to make any headway in that direction. The next step is to create a `--with-import-jvms=<name:path>,[<name:path>,...]`, so that it is possible to simulate a multi-JVM build by e.g.


bash configure --with-jvm-variant=zero --with-conf-name=zero-hotspot
make hotspot
bash configure --with-jvm-variant=server --with-conf-name=combined --with-import-jvms=zero:./build/$PLATFORM/jdk/lib/zero


or something like that.

When that exists and is working, and all downstream users has had time to adapt, then we can remove multi-JVM build support (and boy am I longing for that day).

If you want to help by implementing the `--with-import-jvms` options, you are more than welcome!

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PR: https://git.openjdk.java.net/jdk/pull/5526