BSP Developer's Guide

VxWorks 5.5
BSP Developer’s Guide
Generic Initialization
The remainder of the initialization code is common to both ROM and RAM based
images.
usrConfig.c: usrInit( )
From a BSP writer’s point of view, the main significance of usrInit( ) is that it clears
the bss segment (so that uninitialized C global variables are now zero), and then
calls sysHwInit( ) (in sysLib.c) to initialize the hardware. If memory has been set
up properly, there is little that can go wrong in this routine.
sysLib.c: sysHwInit( )
This is the heart of the BSP initialization code. It must reset all hardware to a
quiescent state so as not to generate uninitialized interrupts later when interrupts
are enabled.
usrConfig.c: usrInit( )
After sysHwInit( ) has completed, control returns to usrInit( ). The last thing
usrInit( ) does is call kernelInit( ) to start the VxWorks kernel. This is the end of
the pre-kernel initialization code. The routine kernelInit( ) does not return. Rather,
it starts the kernel with usrRoot( ) as the first task. It is deep within the
kernelInit( ) routine that interrupts are finally enabled; serious confusion ensues if
not all interrupt sources were disabled and cleared in sysHwInit( ).
You can start the agent as this point if you want to bring up the kernel under
control of the agent. This is an optional step which is not typically done. For more
information, see 3.3.4 Starting the WDB Agent Before the Kernel, p.53.
usrConfig.c: usrRoot( )
The remainder of the VxWorks initialization is done after the kernel has been
started in usrRoot( ). Details are covered in subsequent sections. In this phase, it is
enough if usrRoot( ) can verify that sysHwInit( ) was properly written.
If kernelInit( ) is called but execution fails to reach the start of usrRoot( ), one of
two things are wrong. Either your sysMemTop( ) routine is returning a bogus
address, or, more likely, some device has not been reset and is generating an
interrupt. In the second case, you must modify sysHwInit( ) to reset the
interrupting device.
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