RFR: 8353009: Document target selection flag for Windows AArch64 builds

[Erik Joelsson]

On Thu, 27 Mar 2025 18:32:20 GMT, Saint Wesonga <duke at openjdk.org> wrote:

> I don't think `--build=aarch64-pc-cygwin` is equivalent to `--openjdk-target=aarch64-unknown-cygwin`. The build experts can clarify this but my understanding is that `--openjdk-target` automatically sets the --host and --target options for cross compilation, which I (mistakenly) thought was your scenario. The `--build` option you are using will give you a native build, which is your goal. I filed https://bugs.openjdk.org/browse/JDK-8353066 per your suggestion that it would be good to automatically select the native build instead of requiring a flag for that.

Wait, are you saying you can get a native build to work by setting `--build=aarch64-pc-cygwin`? If so, then that's a better instruction IMO. Building on a windows-aarch64 machine, using x86 cygwin, is what I assumed to be the problematic case. If that can be achieved without configuring an explicit cross compilation build, then that is very much preferred. At the very least the instructions should mention this.

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PR Comment: https://git.openjdk.org/jdk/pull/24267#issuecomment-2759273486