User`s guide

3 Porting a BSP to Custom Hardware

3.2 Getting a Minimal Kernel Running

are provided in 2.2 Boot Sequence, p.7. This section reviews the steps of the

initialization sequence and supplies tips on what to check if a failure occurs at a

particular step.

Initializing ROM-Based Image Types

This section describes the initialization sequence for the ROM-based VxWorks

images vxWorks_rom and vxWorks_resrom_nosym.

romInit.s: romInit( )

At power-up (cold start) the processor begins execution at romInit( ). romInit( )

performs the minimal setup necessary to transfer control to romStart( ) (in

target/config/all/bootInit.c). Most hardware and device initialization is performed

later in the initialization sequence by sysHwInit( ) in sysLib.c.

romInit() is responsible for the following actions:

■

Initializing the processor.

■

Initializing access to target DRAM.

■

Jumping to romStart( ) for further initialization; passing BOOT_COLD on a

cold boot, or the parameter passed from sysToMonitor( ) on a warm boot.

For sample initialization, see the romInit.s file in your reference BSP.

Take care not to add too much initialization code to romInit( ). It is better to do the

minimum amount of initialization at this time and to perform additional

initialization later in the process. Because some BSPs do more initialization in

romInit( ) than necessary, it is wise to review the code from the reference BSP and

remove any initialization code that is unnecessary at this stage of the boot

sequence.

bootInit.c: romStart( )

The text and data segments are copied from ROM to RAM in one of the following

ways:

■

For vxWorks_rom, both the text and data segments are copied to RAM.

■

For vxWorks_resrom_nosym, only the data segment is copied to RAM.