RFR: 8331942: On Linux aarch64, CDS archives should be using 64K alignment by default

[Thomas Stuefe]

On Wed, 8 May 2024 15:14:16 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

> On Linux aarch64, a JVM may encounter three different page sizes: 4K, 64K, and (when run on Mac M1 hardware) 16K.
> 
> Since forgetting to specify `--enable-compatible-cds-alignment` is a common error that is only noticed when running the produced JVM on hardware with different page size, we propose to enable that option by default on Linux aarch64. The cost is a moderate increase in CDS archive size (about 300K).
> 
> I tested this patch on:
> - x64 Linux
> - x64 Linux, crossbuilding to aarch64
> - building natively on aarch64 Linux

Does anyone else have an opinion on this matter? The question is:

"Should we enable cds-compatible alignment in the configure options by default generally, not only for Linux aarch64" ?

This would, in addition to the proposed change affecting Linux on aarch64, also affect MacOS x64. JVMs built there would be able to run, by default, in Rosetta. At the price of sligthly increased archive size of a dozen KB or so.

If nobody objects, I will do that since I like the simplicity of it.

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PR Comment: https://git.openjdk.org/jdk/pull/19142#issuecomment-2101941697