$ bash ./configure --help | head -1
`configure' configures OpenJDK jdk9 to adapt to many kinds of systems.

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 $ grep -i 'jdk.9' doc/building.md
This table lists the OS versions used by Oracle when building JDK 9. Such
OpenJDK 9, the only supported such layer is Cygwin. (Msys is no longer
OpenJDK 9 includes patches that should allow gcc 6 to compile, but this should
should be a JDK of major version *N-1*, so for building JDK 9 a JDK 8 would be
version, since JDK 8 GA might not be able to build JDK 9 on all platforms.
building JDK 9.)
make targets. All source code in JDK 9 is organized so it belongs to a module,