RFR: 8255240: Mobile builds need to exclude some modules [v3]

[Johan Vos]

On Mon, 26 Oct 2020 08:47:35 GMT, Magnus Ihse Bursie <ihse at openjdk.org> wrote:

>> make/modules/java.desktop/Lib.gmk line 38:
>> 
>>> 36: 
>>> 37: ifeq ($(call isTargetOs, android ios), false)
>>> 38:   include lib/Awt2dLibraries.gmk
>> 
>> This change seems too extreme.   You'll have access to the desktop module but any use of the java code in this module will fail since libawt will be missing.  The real fix is to configure the sources and makefiles so the entire code path java.desktop -> native libraries is available but only for the headless toolkit.  The libawt_lwawt should not be included.  This may be difficult since the fontmanager is dependent this native code.  
>> 
>> If this is too difficult, you should just go back and not support the java.desktop module like you had in your first PR version.   Although, every time you add a change like this which moves away from full JRE JCK compatibility, you make it more difficult to upstream these changes.
>
> It would be possible to fix configure so mobile always use headless mode. From my PoV, it seems like the natural approach. Let me know if you need help with fixing that.

The problem with awt_headless is that this depends on X11 (which we don't have on iOS/Android).
I'm not sure what the best approach is. It would need lots of changes to make that work on mobile.
Any help is much appreciated.

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PR: https://git.openjdk.java.net/mobile/pull/10