1.1 Reduction in Static Footprint of Custom JREs

The static footprint of custom JREs has been reduced in two main ways.

• Link Time Optimization (LTO) has been implemented for ARM

  LTO reduces static footprint of JREs that use the minimal JVM and optimizes runtime performance on devices running ARM. For more information about the minimal JVM, see the JVM chapter in Oracle Java SE Embedded Developer's Guide.

• Thumb-2 ISA mode is used for ARM VFP binaries

  For ARM v7, and untested but should work on ARM v6 t2, Thumb-2 ISA mode supports Java Native Interface (JNI) for applications compiled in both ARM and Thumb-2.

1.2 Runtime Performance Improvements

There are several JRE performance improvements at startup. For more information about Java Virtual Machines for embedded devices, see Oracle Java SE Embedded Developer's Guide.

Specifically, the following enhancements have been implemented.

• Client compiler (C1) inlining

  The C1 inlining policy has been expanded by using profile information to improve performance in the minimal and client JVMs. This feature is a tech preview, and it is turned off by default.

  For information about how to enable C1 profiled inlining, see Oracle Java SE Embedded Developer's Guide.

• Class Data Sharing with custom classlists

  Class Data Sharing (CDS) is an existing JDK feature that enables improved JVM startup times and reduced memory consumption. With CDS, you can preload and dump a set of class files to a shared-archive file. This prepared representation of the class files can be shared across multiple JVM processes. With this release of Oracle Java SE Embedded, you can generate your own classlist to a custom location. For more information about using java command-line options to create and preload a custom classlist, see Oracle Java SE Embedded Developer's Guide.

1.3 Enhancements to Headful Application Development

The following changes enhance development of headful applications.

• Support for Java FX components on the Freescale i.MX6 platform

  This release provides support for the JavaFX Base, Graphics, Controls and FXML components on the Freescale i.MX6 processor. For more information about JavaFX components, see Oracle Java SE Embedded Developer's Guide.

• JavaFX multitouch input support

  This release supports touch events for multiple touch input points on the touch screen integrated into the Freescale i.MX6 Sabre device platform. There is touch support for up to 20 touch points, subject to the limits of the hardware and drivers used. Mouse events are synthesized from touch input. See the JavaFX Events tutorial for how to handle touch points.

  Note that there is no support for multitouch gestures.

• Swing/AWT support on X11 for headful development is supported on ARM v5 soft float

  The ARMv5 soft float port now includes Swing/AWT support on X11. See the Oracle Java SE Embedded System Requirements for a full list of devices that offer Swing/AWT support.

1.4 JSR 197 Bundled with Oracle Java SE Embedded

The JSR 197 specification API is equivalent to CLDC 1.0 GCF. The JSR 197 package is provided as a JAR file in the Oracle Java SE Embedded download bundle and can be manually copied into the JRE. For more information, see the section on the JSR 197 JAR in Oracle Java SE Embedded Developer's Guide.

4.1 Java SE API Documentation for the javax.crypto Package

Because of a bug, the current Java SE API documentation for the javax.crypto package does not include compact profile information, but all classes and interfaces in the javax.crypto package are available with all compact profiles. For more information about compact profiles, see the Oracle Java SE Embedded Developer's Guide.

4.2 Raspberry Pi Power Supply

The minimum power supply rating to use on the Raspberry Pi is 800mA. However, unless a higher-rated power supply is used, some problems can occur when the CPU or GPU are under heavy load. For example, USB ports can lose power or the device can suddenly reboot. We recommend the use of a 2A power supply.

4.3 Raspberry Pi Input Events

If you run into problems with dropped input events, try reducing the USB bus speed. First, update the Raspberry Pi firmware:

$ sudo apt-get update
$ sudo apt-get install raspberrypi-bootloader --reinstall

Then, open /boot/cmdline.txt in an editor. On the same line as the other options add dwc_otg.speed=1. Save the file, run sudo sync, and reboot.

This option drops USB speeds from 480Mb/s to 12Mb/s, which resolves issues with a variety of USB devices on the Raspberry Pi.

4.4 JavaFX Generic Bugs

All editions of JavaFX, including the components provided with Oracle Java SE Embedded, exhibit the issues listed at this site: http://javafx-jira.kenai.com.

4.5 AWT Graphics Bug

This bug applies to AWT graphics on certain configurations when rendering is performed through the xrender pipeline. There are some platform X11 bugs that can cause empty or partially empty windows running AWT (not Swing) applications.

As a workaround, xrender is disabled by default in Oracle Java SE Embedded. If you want to test your AWT application to see if it runs without an issue, you can force xrender on with the system property -Dsun.java2d.xrender=true when you launch the application. For example:

$ java -cp AWTApp.jar -Dsun.java2d.xrender=true awtapp.AWTApp 

For more information see the following bug at:
http://bugs.sun.com/view_bug.do?bug_id=8014883

5.1 Server Java Virtual Machine is not Universally Available

The server JVM described in Oracle Java SE Embedded Developer's Guide is only available on the following targets:

• ARM v7 hard float

• ARM v7 soft float

• i586

5.2 Native Memory Tracking Support is Limited on ARM Targets

For ARM devices, the -XX:NativeMemoryTracking=detail java command line option produces a warning and defaults the setting to summary.

5.3 JavaFX 3D Rendering is Only Experimental

There is experimental support for the JavaFX 3D API. This is disabled by default, but can be enabled with the following command-line flag when starting Java:

-Dcom.sun.javafx.experimental.embedded.3d=true