RFR: 8365633: Incorrect info is reported on hybrid CPU [v2]

[Yasumasa Suenaga]

On Fri, 22 Aug 2025 00:14:16 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> @YaSuenag  Is it possible to find from CPUID or OS calls the information about hybrid CPU configuration?
>> 
>> "( 2 P cores, 8 E cores, 2 LP cores)" in you case.  I would prefer if for hybrid CPU we print that info instead of "(7 cores per cpu, 2 threads per core) ".
>> 
>> It is important information when we debug issue on such CPUs.
>
> @vnkozlov I'd like it if we could produce accurate information too but the OS doesn't supply it to us and doing it via CPUID is absurdly complicated. VMVersion is not setup to handle different kinds of cores.

Thanks a lot @dholmes-ora and @vnkozlov !
I updated this PR to show `(hybrid)` as @vnkozlov commented. We can see following strings after this change. I hope this patch confortable for you.


CPU: total 14 (initial active 14) (hybrid) family 6 model 181 stepping 0 microcode 0xffffffff, cx8, cmov, fxsr, ht, mmx, 3dnowpref, sse, sse2, sse3, ssse3, sse4.1, sse4.2, popcnt, lzcnt, tsc, tscinvbit, avx, avx2, aes, erms, clmul, bmi1, bmi2, adx, sha, fma, vzeroupper, clflush, clflushopt, clwb, hv, serialize, rdtscp, rdpid, fsrm, gfni, f16c, cet_ibt, cet_ss, hybrid
CPU Model and flags from /proc/cpuinfo:
model name      : Intel(R) Core(TM) Ultra 5 225U

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PR Comment: https://git.openjdk.org/jdk/pull/26808#issuecomment-3212598807