Build failing when disabling the serialgc

[erik.joelsson at oracle.com]

On 6/20/24 01:01, Sanne Grinovero wrote:
> Hi all,
>
> I was hoping to build a custom JVM which would only have G1GC as a
> garbage collector, for some experiments.
>
> Essentially I'm running:
>
>> bash configure --with-jvm-variants=custom --with-jvm-features=cds,compiler1,compiler2,g1gc,jfr,jni-check,jvmci,jvmti,management,services,link-time-opt --enable-generate-classlist --disable-manpages --with-vendor-name=Experiments
> However then during the "make images" step, this will fail when the
> jmod(s) are being created, with a long sequence of errors such as:
>
> Creating java.security.jgss.jmod
> Error occurred during initialization of VM
> Option -XX:+UseSerialGC not supported
>
> The same build succeeds if I add the "serialgc" in the list of
> selected features.
>
> Should I open a bug report?
> I've verified that both the `master` branch and `jdk23` are affected,
> and so is the `premain` branch on the Leyden fork.
Yes, I think that may be warranted, however see workaround below.
> I'm assuming that it should be supported to build a JVM without the
> serialgc implementation since it's listed as a feature and therefore
> I'd expect it to be OK to disable it, however I'm wondering about this
> explicitly stated need during the jmod building process; is there
> perhaps a specific need for these to be built with the serialgc, or is
> this just a hint meant to make the build more efficient?

There is no specific need, this is just for efficiency. Using the 
"small" java configuration, saves considerable user time for small short 
lived java processes. We currently don't take any limitations in the 
configuration for the built JDK into account when using it as the 
"BUILD_JDK" during the build. Perhaps we should. On the other hand, if 
you are building a limited JDK through configuration options, it can 
often be adviceable to supply a separate BUILD_JDK (for performing the 
build steps that need a JDK N). This can be done by first building a 
standard configuration and then pointing to that JDK image with the 
configure arg --with-build-jdk.

/Erik

> Many thanks,
> Sanne Grinovero
>