[Rev 02] RFR: 8227425: Add support for e-paper displays on i.MX6 devices

[John Neffenger]

On Tue, 28 Apr 2020 23:33:31 GMT, Kevin Rushforth <kcr at openjdk.org> wrote:

>> John Neffenger has refreshed the contents of this pull request, and previous commits have been removed. The incremental
>> views will show differences compared to the previous content of the PR.
>
> Looks good to me.

> Below are some of the more interesting test results.
> * The OpenJDK 11 package ... runs twice as fast as the AdoptOpenJDK build of OpenJDK 13 for some of the tests. ... I plan
>   to investigate the cause of the performance difference.

This is just a note to follow up on that performance problem I saw in December. I think I found the cause of the
problem, and it appears to be fixed in JDK 14 and 15.

The chart below shows the drastic drop in performance before the fix.

![clarahd-focal-copyTo16-2019-12-16](https://user-images.githubusercontent.com/1413266/81237529-b7dfbc80-8fb4-11ea-9673-11e552ecf991.png)

The following flame graph, created by async-profiler, led quickly to an existing Java bug report.

![java-13-openjdk-armhf-600x](https://user-images.githubusercontent.com/1413266/81237598-ea89b500-8fb4-11ea-8928-3b527cf6ac12.png)

See the description at [JDK 13 Performance](https://jgneff.github.io/framebufferY8/2020-05/#jdk-13-performance) for
details. Thank you for the quick fix, @voitylov!

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PR: https://git.openjdk.java.net/jfx/pull/60