RFR: 8253795: Implementation of JEP 391: macOS/AArch64 Port [v9]

[Bernhard Urban-Forster]

On Fri, 12 Feb 2021 12:22:09 GMT, Vladimir Kempik <vkempik at openjdk.org> wrote:

>> Where did this come from - some snippet/example/tech note code? Maybe other people can help figure it out if we provide more info.
>
> This is the version of w^x on-demand switch implemented by microsoft guys. This is enabled only for debug builds.
> @lewurm could you comment here please

Those values can be observed in the debugger, but aren't documented or defined in header files.

This mode was useful for the initial bootstrap of the platform (it helped with missing W^X transitions), but shouldn't be required anymore today. I'm fine with removing it altogether.

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PR: https://git.openjdk.java.net/jdk/pull/2200