RFR(xxs): 8241395: Factor out platform independent code for os::xxx_memory_special()

[Baesken, Matthias]

Hi Thomas, looks good to me.
But you might want to change the copyright year in

http://cr.openjdk.java.net/~stuefe/webrevs/8241395-refactor-reserve-memory-special/webrev.00/webrev/src/hotspot/share/runtime/os.hpp.frames.html

Thanks, Matthias

---------- Forwarded message ---------
From: Thomas Stüfe <thomas.stuefe at gmail.com<mailto:thomas.stuefe at gmail.com>>
Date: Sat, Mar 21, 2020 at 1:40 PM
Subject: RFR(xxs): 8241395: Factor out platform independent code for os::xxx_memory_special()
To: Hotspot dev runtime <hotspot-runtime-dev at openjdk.java.net<mailto:hotspot-runtime-dev at openjdk.java.net>>

Hi,

may I please have reviews for this little cleanup.

A while ago we factored out platform independent behavior for os::reserve_memory() and friends to os.cpp and relegated platform dependent code to os::pd_reserve_memory() etc. This change does the same for os::reserve_memory_special() and os::release_memory_special().

Only Linux and Windows are affected since only they have meaningful implementations for UseLargePages.

It also adds a small comment about the NMT Tracker object.

In addition it asserts - now for all platforms, it used to do this only on Linux - that if both requested address and alignment are given to os::reserve_memory_special() the requested address should at least be aligned to the given alignment (the arguments should be mutually exclusive and I plan to clean this up further).

Issue: https://bugs.openjdk.java.net/browse/JDK-8241395
webrev: http://cr.openjdk.java.net/~stuefe/webrevs/8241395-refactor-reserve-memory-special/webrev.00/webrev/

Thanks, Thomas