RFR: 8378675: PPC64: increase instruction cache line size [v2]

[Martin Doerr]

On Wed, 25 Feb 2026 14:56:15 GMT, David Briemann <dbriemann at openjdk.org> wrote:

>> Set the instruction cache line size for Power to 128 bytes.
>> 
>> Add functions to retrieve the data cache line size and instruction cache line size from the system (AIX & Linux).
>
> David Briemann has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - add comments that explain getconf behavior
>  - update copyright headers

Thanks! `os::get_dcache_line_size()` and `os::get_icache_line_size()` can also be implemented for BSD and Windows if needed in the future.

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Marked as reviewed by mdoerr (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/29918#pullrequestreview-3855525324