RFR: 8364248: Separate memory limit detection from determining its size [v4]

[Joel Sikström]

On Thu, 31 Jul 2025 05:19:15 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

>> Joel Sikström has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   os:: unification in allocatable_memory_limit
>
> src/hotspot/os/posix/os_posix.cpp line 813:
> 
>> 811: 
>> 812:   // No limit
>> 813:   return SIZE_MAX;
> 
> This would be a very nice place to hook in the function I proposed you add, the sister function to `os::vm_min_address()`, let's call it `os::vm_max_address()`.
> 
> Looking through the ZGC sources, this is the functionality I meant: https://github.com/openjdk/jdk/blob/559795b0eb8061325127fa9fdf8b80617fe47166/src/hotspot/cpu/aarch64/gc/z/zAddress_aarch64.cpp#L45
> 
> For platforms that don't have that implementation, you can still return SIZE_MAX as fallback.

Yes, this could be nice to have in the future, and would likely be a larger re-write.

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PR Review Comment: https://git.openjdk.org/jdk/pull/26530#discussion_r2244642891