[Help] About the two debug modes of ARM

[Help] About the two debug modes of ARM

[xingxing pan]

From the ARM11 reference manual, I know ARM11 has two debug modes, the
Halting mode and the Monitor Mode.
When we use debuggers to debug a program, often there are also two
modes. The remote debugging, the debugger runs on the host, the
debuggee runs on the target, and the debugger communicates with the
core through something like JTAG. The native debugging, the debugger
and debuggee run on the same computer.

Here are my questions.
(1)Dose the Halting mode and the Monitor mode correspond to Remote
debugging and Native debugging respectively?
(2)Some cores like ARM920 don't have the Monitor mode. Dose it means
that when we are in native debugging on that cores, we can not use the
hardware breakpoints and watchpoints?

Thank you!

Forandom

RE: [Help] About the two debug modes of ARM

[Will Deacon]

Hi,

> From the ARM11 reference manual, I know ARM11 has two debug modes, the
> Halting mode and the Monitor Mode.
> When we use debuggers to debug a program, often there are also two
> modes. The remote debugging, the debugger runs on the host, the
> debuggee runs on the target, and the debugger communicates with the
> core through something like JTAG. The native debugging, the debugger
> and debuggee run on the same computer.

Right, those are the usual two debugging scenarios.
 
> Here are my questions.
> (1)Dose the Halting mode and the Monitor mode correspond to Remote
> debugging and Native debugging respectively?

Halting Mode means that the core is being debugged by an external
JTAG debugger. Monitor mode means that the debugging is performed
natively via co-processor or memory-mapped debug registers and 
debug events are handled via exceptions.

> (2)Some cores like ARM920 don't have the Monitor mode. Dose it means
> that when we are in native debugging on that cores, we can not use the
> hardware breakpoints and watchpoints?

You will need an external debugger in order to use hardware watchpoints
or breakpoints on the ARM920. The 926 has monitor mode implemented using
the EmbeddedICE-RT logic, so you can use the hardware resources there [with
the relevant Kernel support].

Hope that helps,

Will