[crac] RFR: RFC: -XX:CPUFeatures=0xnumber for CPU migration [v24]

[Jan Kratochvil]

On Wed, 31 May 2023 13:54:48 GMT, Jan Kratochvil <jkratochvil at openjdk.org> wrote:

>> src/hotspot/os_cpu/linux_x86/os_linux_x86.cpp line 224:
>> 
>>> 222:       stub = VM_Version::cpuinfo_cont_addr();
>>> 223:     }
>>> 224:   } else
>> 
>> Why do we need this block? Is not this duplicating logic from line 251?
>
> It was needed for some previous variant of the patch and it is a leftover. Removed. Sorry for not self-reviewing this version of my patch.

It is in fact needed: https://github.com/openjdk/crac/blob/08c2c0f2b140b1011fec39a1a83037df8e59577d/src/hotspot/os_cpu/linux_x86/os_linux_x86.cpp#L217
During CRaC restore there is somehow no Java thread created yet that time. I do not understand this much so I left it there as working but maybe some Java thread should be initialized earlier?

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PR Review Comment: https://git.openjdk.org/crac/pull/41#discussion_r1213180053