[crac] RFR: 8372933: [CRaC] Restore failed due to incompatible or missing CPU features, try using -XX:CPUFeatures=0xfoo, 0xbar on checkpoint

[Jan Kratochvil]

On Tue, 2 Dec 2025 13:52:49 GMT, Timofei Pushkin <tpushkin at openjdk.org> wrote:

>> src/hotspot/share/include/crlib/crlib_image_constraints.h line 66:
>> 
>>> 64:   // if multiple images are considered for restore this method should always return false.
>>> 65:   // For failed require_bitmap it will copy the expected value to the provided buffer.
>>> 66:   bool (*is_failed)(crlib_conf_t *, const char *name, unsigned char *value_return);
>> 
>> We should not change the API in a breaking way like this; rather add a new, more suitable method (a size-based check can validate if the method can be used).
>> 
>> The change as you add it accommodates (based on type) only bitmaps, not labels, and does not do any checks on the buffer size.
>
> Have there been any JDK releases since we introduced this API? I think not, then we should still be free to change it, shouldn't we?
> 
> I haven't looked into the bug, so cannot comment on the change itself, just noticed this message.

Maybe there should be `is_failed_label` and `is_failed_bitmap` but I just wanted something to get it running.

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PR Review Comment: https://git.openjdk.org/crac/pull/278#discussion_r2581307614