Microsoft Windows Embedded CE 6.0 Exam Preparation Kit

The debugging features of Windows Embedded CE rely on development workstation components and the target device, and require specific settings and hardware support. Without a connection between the development workstation and the target device, debug information and other requests cannot be exchanged. If this communication link breaks — for example, because you stop the debugger on the development workstation without first unloading the target-side debugging stub — the run-time image might stop responding to user input while waiting for the debugger to resume code execution after an exception occurred.

After this lesson, you will be able to:

¦ Enable the Kernel Debugger for a run-time image.

¦ Identify the KITL requirements.

¦ Use the Kernel Debugger in a debugging context.

Estimated lesson time: 20 minutes.

Enabling the Kernel Debugger

As discussed in Lesson 1, the development environment for Windows Embedded CE 6.0 includes a Kernel Debugger that enables developers to step through and interact with code running on a CE target device. This debugger requires you to set kernel options and a communication layer between the target device and the development computer.

OS Design Settings

To enable an OS design for debugging, you must unset the environment variables IMGNODEBUGGER and IMGNOKITL so that Platform Builder includes the KdStub library and enables the KITL communication layer in the Board Support Package (BSP) when building the run-time image. Platform Builder provides a convenient method to accomplish this task. In Visual Studio, right-click the OS design project and select Properties to display the OS Design property pages dialog box, switch to the Build Options pane, and then select the Enable Kernel Debugger and Enable KITL check boxes. Chapter 1, 'Customizing the Operating System Design,' discusses the OS Design property pages dialog box in more detail.

Selecting a Debugger

Having enabled KdStub and KITL for a run-time image, you can select a debugger to analyze the system on the target device in the communication parameters for your target device. To configure these parameters, display the Target Device Connectivity Options dialog box in Visual Studio by opening the Target menu and selecting Connectivity Options, as explained in Chapter 2, 'Building and Deploying a Run­Time Image.'

By default, no debugger is selected in the connectivity options. You have the following debugger choices:

¦ KdStub This is the software debugger for the kernel and applications to debug system components, drivers, and applications running on a target device. KdStub requires KITL to communicate with Platform Builder.

¦ CE Dump File Reader Platform Builder provides you with an option to capture dump files, which you can then open by using the CE dump-file reader. Dump files enable you to study the state of a system at a particular point in time and are useful as references.

¦ Sample Device Emulator eXDI 2 Driver KdStub cannot debug routines that the system runs prior to loading the kernel, nor can it debug interrupt service routines (ISRs), because this debugging library relies on software breakpoints. For hardware-assisted debugging, Platform Builder includes a sample eXDI driver that you can use in conjunction with a joint test action group (JTAG) probe. The JTAG probe enables you to set hardware breakpoints handled by the processor.

NOTE

Hardware-assisted debugging

For detailed information about hardware-assisted debugging, see the section 'Hardware-assisted Debugging' in the Windows Embedded CE 6.0 Documentation, available on the Microsoft MSDN Web site at http://msdn2.microsoft.com/en-us/library/aa935824.aspx.

KITL

As illustrated in Figure 4-1 at the beginning of this chapter, KITL is an essential communication layer between the development computer and the target device and must be enabled for Kernel Debugger support. As the name implies, KITL is completely hardware independent and works over network connections, serial cables, Universal Serial Bus (USB), or any other supported communication mechanism, such as Direct Memory Access (DMA). The only requirement is that both sides (development computer and target device) support and use the same interface. The most common and fastest KITL interface for the device emulator is DMA, as illustrated in Figure 4-7. For target devices with a supported Ethernet chip, it is typically best to use the network interface.

Figure 4-7 Configuring the KITL communication interface

KITL supports the following two methods of operation:

¦ Active mode By default, Platform Builder configures KITL to connect to the development computer during the start process. This setting is most useful for kernel and application debugging during the software-development cycle.

¦ Passive mode By clearing the check box Enable KITL on Device Boot, you can configure KITL for passive mode, meaning Windows Embedded CE initializes the KITL interface, but KITL does not establish a connection during the startup process. If an exception occurs, KITL makes an attempt to establish a connection to the development computer so that you can perform JIT debugging. Passive mode is most useful when working with mobile devices that do not have a physical connection to the development computer at startup.

NOTE

KITL modes and boot arguments

The Enable KITL on Device Boot setting is a boot argument (BootArgs) that Platform Builder configures for the boot loader. For more information about boot loaders and their advantages during the BSP development process, see the section 'Boot Loaders' in the Windows Embedded CE 6.0 Documentation, available on the Microsoft MSDN Web site at http://msdn2.microsoft.com/en- us/library/aa917791.aspx.