RFR: 8378675: PPC64: increase instruction cache line size [v3]

[Martin Doerr]

On Thu, 26 Feb 2026 16:13:28 GMT, Martin Doerr <mdoerr at openjdk.org> wrote:

>> src/hotspot/share/runtime/os.hpp line 1080:
>> 
>>> 1078: 
>>> 1079:   static int get_dcache_line_size();
>>> 1080:   static int get_icache_line_size();
>> 
>> There seems to be an inconsistency: besides these declarations there are also (unused) declarations in os::Linux and os::Aix. The definitions and references, though, are for these declarations (in class os). Problem with the declarations in os is that not all OSes have implementations.
>> I think this needs to be resolved.
>
> Doesn't this work as designed? `cpu_microcode_revision()` doesn't have implementations for all platforms, either. The 2 new functions can be implemented on more OSes on demand.

But, your point that the changes in os_aix.hpp and os_linux.hpp are unused declarations is true. I think they should get reverted.

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PR Review Comment: https://git.openjdk.org/jdk/pull/29918#discussion_r2860000989