RAM 6.0 BUX II Series Betriebsanweisung PDF herunterladen (Seite 53)

2 Overview of a BSP

2.4 The Development Environment

Native Debug ROMs

In some cases, the board manufacturer provides flash software that can be used to

help debug the VxWorks BSP. To be useful, a ROM monitor must have breakpoint

support. It is also helpful to have a mechanism by which to download the image.

An example of a debug ROM is ppcbug, which is provided by Motorola.

ROM Emulator

A ROM emulator is a device that plugs into a ROM socket on your target system

and emulates the behavior of a ROM part.

From the target system, this device functions as a ROM (with a possible difference

in timing behavior). From the development host, a ROM emulator allows you to

see every transaction visible to the ROM; typically, either all access to memory or

all access to ROM. At a minimum, this device allows you to see what instructions

are being executed during the initial phases of the boot sequence.

A ROM emulator eliminates the need to program flash devices and may allow you

to see the steps of program execution. However, it does not allow access to the

processor registers. A ROM emulator can be used in conjunction with LED or

kprintf( ) debugging (see Primitive Tools, p.44). Note that this combination is better

than either method by itself.

On-Chip Debugging (OCD) Devices

For BSP debugging, a hardware debugger is often a better solution than any of the

basic tools presented above. Many modern processors provide a debug bus that

allows access by external debugging hardware to useful processor information

such as register values, interrupt mask, and other aspects of the processor’s

internal state. One example of this type of interface is the JTAG port available on

many PowerPC, MIPS, ARM, Intel XScale, and other processors. OCD devices,

such as the Wind River ICE, can access this port. This access allows you to begin

debugging much earlier in the BSP development process.

An OCD device provides access to the target processor’s registers, which allows

you to start using the OCD before any VxWorks initialization code is written. In

fact, this type of tool is often used to determine how the initialization code must

set specific processor configuration registers.

1 2 ... 48 49 50 51 52 53 54 55 56 57 58 ... 188 189

Keine Kommentare

RAM 6.0 BUX II Series Betriebsanweisung Seite 53