[OpenJDK 2D-Dev] RFR: 8253795: Implementation of JEP 391: macOS/AArch64 Port [v9]

[Andrew Haley]

On Fri, 5 Feb 2021 17:20:55 GMT, Anton Kozlov <akozlov at openjdk.org> wrote:

>> src/hotspot/cpu/aarch64/vm_version_aarch64.hpp line 93:
>> 
>>> 91:     CPU_MARVELL   = 'V',
>>> 92:     CPU_INTEL     = 'i',
>>> 93:     CPU_APPLE     = 'a',
>> 
>> The `ARM Architecture Reference Manual ARMv8, for ARMv8-A architecture profile` has 8538 pages, can we be more specific and point to the particular section of the document where the CPU codes are defined?
>
> They are defined in 13.2.95. MIDR_EL1, Main ID Register. Apple's code is not there, but "Arm can assign codes that are not published in this manual. All values not assigned by Arm are reserved and must not be used.". I assume the value was obtained by digging around https://github.com/apple/darwin-xnu/blob/main/osfmk/arm/cpuid.h#L62

Anton, this paragraph looks like an excellent comment.

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PR: https://git.openjdk.java.net/jdk/pull/2200