[crac] RFR: 8355974: [CRaC] Move CPUFeatures verification to the parent process of JVM [v16]

[Jan Kratochvil]

On Mon, 19 May 2025 07:48:02 GMT, Timofei Pushkin <tpushkin at openjdk.org> wrote:

>> Jan Kratochvil has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Wrap cpufeatures_store() by VM_Version::ignore_cpu_features()
>
> src/hotspot/share/runtime/crac.cpp line 123:
> 
>> 121:         VM_Version::CPUFeaturesBinary data;
>> 122:         if (!VM_Version::cpu_features_binary(&data)) {
>> 123:           // This backend does not use CPUFeatures. That is OK.
> 
> In [my suggestion](https://github.com/openjdk/crac/pull/227#discussion_r2087372826) I placed this check before `_engine->prepare_user_data_api()` because if the backend doesn't support CPU features there is no point in querying the engine for its support (and possibly erroring on `CracEngine::ApiStatus::ERR`): we would ask the user to fix the engine issue only for them to find out their backend cannot use this feature anyway.
> 
> But since this can be bypassed by ignoring CPU features I'm OK with postponing fixing this together with that.

OK, I have used your code. Do you think about some backend which would not support user data?
b7c976c4a86268ee2455176003d603be6e988955

-------------

PR Review Comment: https://git.openjdk.org/crac/pull/227#discussion_r2095669272