User`s guide

VxWorks

BSP Developer’s Guide, 6.0

mistake in BSP development is the failure to ensure that all interrupt sources are

quiescent prior to enabling interrupts. If this is not done before the call to

kernelInit( ), the system typically hangs or fails, causing confusion for the BSP

developer because the source of the problem is not obvious.

If kernelInit( ) is called but execution fails to reach the start of usrRoot( ), or if the

system behaves erratically in other ways after the call to kernelInit( ), usually it is

one of two problems. Either sysMemTop( ) is returning a bad address or, more

likely, some device has not been reset and is generating an interrupt. In the latter

case, you must modify sysHwInit( ) to reset the interrupting device.

To find the source of the interrupt, start by figuring out the interrupt vector being

generated, applying any of the following techniques:

■

Use a logic analyzer to look for instruction accesses to the interrupt vector

table.

■

Use an OCD device to set breakpoints in the interrupt vector table.

■

Modify sysHwInit( ) to mask suspected interrupt vectors through an interrupt

controller.

■

Modify sysHwInit( ) to connect debugging routines to the suspected interrupt

vectors using intVecSet( ) (you cannot use intConnect( ) because it calls

malloc( ) and the VxWorks memory allocator is not yet initialized).

usrConfig.c: usrRoot( )

The remainder of the VxWorks initialization is done after the kernel is started in

usrRoot( ). The details of the initialization process are covered in subsequent

sections. In this phase, it is enough for usrRoot( ) to verify that sysHwInit( ) is

properly written.

At this point, you have a working kernel but no device drivers. The only drivers

required by VxWorks are a timer and possibly an interrupt controller. Most BSPs

also have serial drivers.

3.2.5 Starting the WDB Agent Before the Kernel

This step is optional when creating a new BSP and is rarely performed. However,

if you have a slow download environment, you may want to put everything in

NOTE: This procedure applies only to images built from the command line.