[jdk11u-dev] RFR: 8253638: Cleanup os::reserve_memory and remove MAP_FIXED [v2]

[Vladimir Kempik]

On Tue, 2 Nov 2021 07:10:34 GMT, Vladimir Kempik <vkempik at openjdk.org> wrote:

>> Hello, please review this backport of JDK-8253638  to jdk11u-dev, its a prerequest for JDK-8255254 ( and MAP_JIT support as well) which is mac-aarch64 backport prerequest
>
> Vladimir Kempik has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Fix up windows

Hello Thomas.
I have built solaris (hotspot only, as harfbuzz is broken currently in openjdk11u).

I think it would be just these two.

https://bugs.openjdk.java.net/browse/JDK-8255254 Split os::reserve_memory and os::map_memory_to_file interfaces
https://bugs.openjdk.java.net/browse/JDK-8234930 Use MAP_JIT when allocating pages for code cache on macOS


as I first did 8255254, and it wasn't easy because of missing 8253638.
Then I have tried to do 8234930 on top of 8255254 and realised I really need 8253638.
So I think we can make it to just these three - 8253638 8255254 8234930

This backport is based on PR for jdk15u-dev backport ( https://github.com/openjdk/jdk15u-dev/pull/125 )
Plus solaris support and os_windows.cpp was very different from jdk15u
Also few more NULL argument removals from call to reserve_memory in SafePointMechanism.cpp

We have in-house MAP_JIT patch ( used for zulu11 for mac-aarch64) and it's very different from these three. Not sure we really wanna go this route and differ so much from upstream

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PR: https://git.openjdk.java.net/jdk11u-dev/pull/574