[OpenWrt-Devel] Java compiler

Dana Myers k6jq at comcast.net
Sat Apr 11 10:35:23 EDT 2020

On 4/10/2020 1:48 PM, W. Michael Petullo wrote:
> Has anyone tried to build a Java compiler package for OpenWrt? I am
> investigating doing this. I see the lang/jamvm JVM, but no compiler
> akin to devel/gcc or lang/golang. I have packaged a number of things,
> but I suspect this will be a bit more of a challenge. Hence my question
> here.

In a related context, I recently wrote:
I updated classpath and jamvm over 5 years ago to support a project I am no longer
involved with. Upstream jamvm has not changed in almost 6 years, with language
support frozen at Java 8. Upstream classpath has not changed in 8 years, with
language support frozen at Java 7. (My project was specifically compiled at v1.5).

jamvm depends on classpath; if classpath is removed, jamvm should be as well.
I am no longer in a position to actively maintain either of these packages.

So, Java support in OpenWRT arguably requires starting with the JVM and
making sure it supports a modern revision of the language. Then, either
updating classpath to a modern version or possibly adopting the classlib from
OpenJDK. With this done, you may be able to run Java classes compiled with
modern tools; IIRC, support for v1.5 compilation was removed from the
JDK several versions ago.

[ Also, My application pared-down classpath to just the necessary classes; even if
the OpenWRT platform in use has a lot of memory, classloading from flash
is _slow_. ]

Running JDK (javac) per se on OpenWRT strikes me as not being worth the effort.
Just getting the Java run-time environment modernized on OpenWRT is a
full-time job :-)


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