BSP Developer's Guide

3
Creating a New BSP
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 ICE to set breakpoints in the interrupt vector table.
Modify sysHwInit( ) to mask suspected interrupt vectors via an interrupt
controller.
■
Modify sysHwInit( ) to connect debug routines to the suspected interrupt
vectors using intVecSet( ) (you cannot use intConnect( ) because it calls
malloc( ) and the VxWorks memory allocator has not yet been initialized).
At this point you have a working kernel, but no device drivers. The only drivers
required by VxWorks is a timer and possibly an interrupt controller. Most BSPs
also have serial drivers. Adding basic driver support to VxWorks is described in
3.4 Using a Minimal Kernel, p.55.
3
3.3.4 Starting the WDB Agent Before the Kernel
NOTE: This procedure applies only to images built from the command line.
This step is optional and is rarely done at Wind River when creating a new BSP. The
disadvantages to starting the agent before the kernel are:
■
■
Once the hardware initialization code is written, bringing up the kernel takes
less time than bringing up the agent. Because most developers consider a
working kernel to be the bigger milestone, start with the kernel.
Starting the agent before the kernel does not really help get the basic kernel
working. This is because the basic kernel adds little to what you have written
already; just a timer driver and possibly an interrupt controller, which are
simple devices.
■
Starting the agent before the kernel limits you to system mode debugging.
The only reason to start the agent early is if you have a very slow download
environment. In that case, you may want to put everything in ROM as early as
possible to save download cycles.
Starting the agent before the kernel is described in Tornado User’s Guide: Setup and
Startup. The following two sections provide important additional information.
53