[OpenJDK 2D-Dev] RFR: 8254024: Enhance native libs for AWT and Swing to work with GraalVM Native Image

[Andrii Rodionov]

On Wed, 9 Dec 2020 01:26:08 GMT, Phil Race <prr at openjdk.org> wrote:

>> No, we produce only one image. The headless/non-headless mode is defined by the system property `-Djava.awt.headless=...`.
>> Here is a command example for native image generation:
>> `$ ~/graalvm-ce-java11-21.0.0-dev/bin/native-image -H:ConfigurationFileDirectories=./configs -Djava.awt.headless=true AWTFixExample`
>> 
>> With `-Djava.awt.headless=false` to the gcc linker we pass `libawt.a` and `libawt_headless.a`
>> With `-Djava.awt.headless=true` to the gcc linker we pass `libawt.a` and `libawt-xawt.a`
>> If the generated image demands `libmlib_image.a` it will be also linked.
>
>> No, we produce only one image. The headless/non-headless mode is defined by the system property `-Djava.awt.headless=...`.
>> Here is a command example for native image generation:
>> `$ ~/graalvm-ce-java11-21.0.0-dev/bin/native-image -H:ConfigurationFileDirectories=./configs -Djava.awt.headless=true AWTFixExample`
>> 
>> With `-Djava.awt.headless=false` to the gcc linker we pass `libawt.a` and `libawt_headless.a`
>> With `-Djava.awt.headless=true` to the gcc linker we pass `libawt.a` and `libawt-xawt.a`
>> If the generated image demands `libmlib_image.a` it will be also linked.
> 
> -Djava.awt.headless is a runtime property not a build time property. So you are doing domething very weird.
> How does that image with "false" run a UI app ? It can't. And yet the one with "true" still can run without an xserver, except it will not start unless you have X11 libs installed - and I am *reasonably* sure you aren't statically linking all the system provided libraries ... I hope ...
> 
> So how does a "user" use all of this ? Seems they must create their own app by native compile + linking.
> Can they create an image that can run any java app, or must the app like AWTFixExample be linked in to the image ?

@prrace It may be also useful to look at how we define a set of static libraries:
https://github.com/oracle/graal/blob/9390324021ab7b6ed391f2c8f62be490a7ab13db/substratevm/src/com.oracle.svm.hosted/src/com/oracle/svm/hosted/jdk/JNIRegistrationAwt.java#L104

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PR: https://git.openjdk.java.net/jdk/pull/562