Really appreciate the updated build documentation for JDK9.

But the "Building on arm/aarch64" is misleading if not prejudicial:
<quote>
This is not recommended. Instead, see the section on Cross-compiling.
</quote>

Aarch64 can do full clean builds on spinning disks in 8 minutes or less. A rebuild (eg. nothing to make) takes about 4 seconds.

Of course this is on a commercially available workstation/server class machine, not a Rpi or hacked smart phone.

An 8 core/8GB virtualized slice of a machine takes about 30 minutes to do a full clean build. Not as pleasant, but usable.

I'm not sure what timings were considered acceptable for the other platforms (has anyone times a 4 core/ 4GB SPARC build recently?). But I'd suggest that the 8 core/8 GB config would be a useful suggested minimum.