[crac] RFR: 8353243: [CRaC] Show all options in engine help [v2]

[Radim Vansa]

On Wed, 2 Apr 2025 14:52:52 GMT, Timofei Pushkin <tpushkin at openjdk.org> wrote:

>> src/hotspot/share/runtime/crac_engine.cpp line 415:
>> 
>>> 413:   }
>>> 414: 
>>> 415:   if (strcmp(id, "crexec") == 0) {
>> 
>> I don't think you need the `crexec` check here. I would also drop the logging parts, unlikely to be useful in the practice.
>
> It may be an external C/R engine with `exec_location` option — JVM won't block the user from using this option so it shouldn't be included here. It is possible for this engine to also be named "crexec" so this check is not fully robust (it would be more robust to record that we've loaded _our crexec_) but I've decided this is a decent balance between robustness and code simplicity.
> 
> Regarding the logs, agree, I'll remove them.

Let's ignore the theoretical ambiguity for `crexec`...

> It may be an external C/R engine with exec_location option — JVM won't block the user from using this option so it shouldn't be included here.

I do not get the message. If an external engine supports that option, then JVM should provide the information (maybe the engine wants to load some shared library that is in the lib directory?). It shouldn't treat `our crexec` differently than any external engine.

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PR Review Comment: https://git.openjdk.org/crac/pull/220#discussion_r2030733676