Building OpenJDK 19 from source?

Dear codeguru,

I have been reading both https://openjdk.org/groups/build/doc/building.html and I have found this tutorial incomplete
and difficult in places, if not as somewhat out of date. I am trying to build a working, independent OpenJDK 19, with compiler and runtime, from source code and resource files.

I am interested in the Windows 64 bit, Linux 64 bit and Mac platforms. I wish to cross compile, which means, I think, compile for separate operating system platforms.
I have Windows 10 or Windows 11, both 64 bit, available to me. I am having trouble getting anywhere using Cygwin 64 bit.

-I am using jdk-18.0.2 as my boot jdk. I believe that I have successfully installed the dependences of git, autoconf, make, zip and unzip.
I have changed directory to the jdk directory and run the command bash configure --with-boot-jdk /home/User/jdk-18.0.2/,
where I have put a binary version of the Windows OpenJDK to use as a boot jdk. But my problem is that I only get the following error,
which doesn't tell me what to do:


checking build system type... Invalid configuration `/home/User/jdk-18.0.2/': machine `/home/User/jdk-unknown' not recognized
configure: error: /usr/bin/bash /home/User/jdk/make/autoconf/build-aux/config.sub /home/User/jdk-18.0.2/ failed
configure exiting with result code 1

What do I do from here?

-Is it possible to build a working OpenJDK 19 on Windows 10 or Windows 11 without using Microsoft Visual Studio, but just a good version of gcc > 4.3 ?

-Is there someone out there, or associated with codeguru, who can command for command, provide me with a complete tutorial for what I can do to download the OpenJDK 19 source code
and resource files correctly, set up one Windows 64 bit environment, with any path or background commands, with all required dependencies, and then build to a successful conslusion?
I cannot get anywhere, and the tutorials on this subject are not solving my problems. :(