Virtual Machines

Java executes in a Virtual Machine

Java class file

Java compiler Byte Codes Java Virtual

Machine

Android apps execute in a Virtual Machine

Java class file

Java compiler Byte Codes DEX Codes

Dalvik Virtual

Machine

Common Language Runtime (CLR) apps execute in a Virtual Machine

C#, VB.NET,Etc…

Language compiler

Common Intermediate

Language

Common Language Runtime

Android App Testing and Virtual MachinesAndroid applications are supported by a variety of vendor devices, and these have their own CPUs. The Android Developer Toolkit creates virtual devices so that we can test our applications without the need of real hardware. These virtual devices are faithful to the hardware, and provide a remarkably good test of our apps. The image at the left is from a virtual Android device. The downside is that these virtual devices tend to be slow.

Intel manufacturers the Atom™ processor, which is one of the CPUs used in android devices. Plus, they manufacture the CPU for most of the development machines. Needless to say, they know how to put the two together and make their virtual Atom CPU run very fast. The technology for this is called Virtualiation. Virtualization is a feature of the hardware (in our case, the Core™ i5 hardware) that roughly speaking allows virtual instructions to execute natively on the real hardware. The result is vastly improved performance of the virtual device.

Our interest is in making Android simulators run fast, but the same technology allows Linux run as a guest in the Windows operating system pretty much like it owned the hardware.

The Core™i5 processor in the Lenovo Ultrabook Twist computers supports Virtualization. It is turned off by default, and the remainder of this tutorial explains how to enable this feature.

Enabling Virtualization requires a change in the BIOS (Basic Input/Output System). The BIOS is a part of the built in instructions responsible for configuring your computer during the boot process. The BIOS is deliberately difficult to access because most users don’t/shouldn’t make changes to these parameters.

Do not alter the BIOS on a whim. The result could be a useless computer!

To Enter the BIOS menu• Turn your computer off• Press the start button• Press the Enter key repeatedly while your

Computer is booting

You may need to repeat these steps a couple of times before BIOS menu below appears.

Activation of the BIOS setup utility is achieved byPressing the F1 key.

Note that the you must hold down the RED Fn key and press the corresponding F key at the top of the keyboard.

Be careful. You can disable your computer from the BIOS!!

The screen for enabling virtualization is accessed from the Security tab.

Use the left and right arrow keys to highlight the security tab.

Press Enter when the security tab is highlighted to enter the sub-menu, below.

Use the up and down arrows to select the Virtualization option.

Press Enter when Virtualization is highlighted to show the virtualization options screen (below)

Use the + and – keys to toggle between Disabled and Enabled.

Use the up and down arrows to switch between options.

Press F10 (don’t forget the red Fn key) to save and exit.

The Final StepLaunch the SDK manager and ensure that HAXM is installed. If it is not, check the box and tell the SDK manager to install it. This appears to simply download the installer, and place it in the extras sub- folder in your android-sdks folder. Go to the sub-folder and launch the installer.

Note especially that Virtualization will only make a difference on the virtual devices based on an Atom™ processor.