On Wed, 3 Feb 2021 20:01:15 GMT, Anton Kozlov <akoz...@openjdk.org> wrote:
>> Please review the implementation of JEP 391: macOS/AArch64 Port.
>>
>> It's heavily based on existing ports to linux/aarch64, macos/x86_64, and
>> windows/aarch64.
>>
>> Major changes are in:
>> * src/hotspot/cpu/aarch64: support of the new calling convention (subtasks
>> JDK-8253817, JDK-8253818)
>> * src/hotspot/os_cpu/bsd_aarch64: copy of os_cpu/linux_aarch64 with
>> necessary adjustments (JDK-8253819)
>> * src/hotspot/share, test/hotspot/gtest: support of write-xor-execute (W^X),
>> required on macOS/AArch64 platform. It's implemented with
>> pthread_jit_write_protect_np provided by Apple. The W^X mode is local to a
>> thread, so W^X mode change relates to the java thread state change (for java
>> threads). In most cases, JVM executes in write-only mode, except when
>> calling a generated stub like SafeFetch, which requires a temporary switch
>> to execute-only mode. The same execute-only mode is enabled when a java
>> thread executes in java or native states. This approach of managing W^X mode
>> turned out to be simple and efficient enough.
>> * src/jdk.hotspot.agent: serviceability agent implementation (JDK-8254941)
>
> Anton Kozlov has updated the pull request incrementally with six additional
> commits since the last revision:
>
> - Merge remote-tracking branch 'origin/jdk/jdk-macos' into jdk-macos
> - Add comments to WX transitions
>
> + minor change of placements
> - Use macro conditionals instead of empty functions
> - Add W^X to tests
> - Do not require known W^X state
> - Revert w^x in gtests
src/hotspot/os_cpu/bsd_aarch64/os_bsd_aarch64.cpp line 403:
> 401: }
> 402:
> 403: return false; // Mute compiler
Is this comment needed?
src/hotspot/os_cpu/bsd_aarch64/os_bsd_aarch64.cpp line 420:
> 418: size_t os::Posix::_compiler_thread_min_stack_allowed = 72 * K;
> 419: size_t os::Posix::_java_thread_min_stack_allowed = 72 * K;
> 420: size_t os::Posix::_vm_internal_thread_min_stack_allowed = 72 * K;
Those are slightly larger than their x86_64 counter parts. Are they
conservative/aggressive values? How did we arrive at those?
src/hotspot/os_cpu/bsd_aarch64/os_bsd_aarch64.cpp line 652:
> 650:
> 651: void os::setup_fpu() {
> 652: }
Is there really nothing to do here, or does still need to be implemented? A
clarification comment here would help/.
-------------
PR: https://git.openjdk.java.net/jdk/pull/2200
