RFR: 8255917: runtime/cds/SharedBaseAddress.java failed "assert(reserved_rgn != 0LL) failed: No reserved region" [v3]

[Thomas Stuefe]

On Mon, 14 Dec 2020 19:14:32 GMT, Yumin Qi <minqi at openjdk.org> wrote:

>> LGTM
>
> @iklam @calvinccheung Thanks for review. I will wait for @tstuefe input for integration.

Hi Yumin, 

I don't understand the special handling in NMT.

Unix: We reserve a region, split it, tell NMT about the split (see posix version of os::split_reserved_memory), then later release both parts separately. 
Windows: 
1) use_archive_base_addr = true: we allocate the spaces separately, later release them separately
2) use_archive_base_addr = false: we allocate total space, leave it unsplit, then later release the total space.

Where is this new NMT coding needed? 

Thanks, Thomas

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PR: https://git.openjdk.java.net/jdk/pull/1750