Re: hardware support for gdb?

["mohanlal jangir" <mohanlaljangir at hotmail dot com>]

> >
> > Really!! Does even single stepping also not require any hardware
support?
>
> I'm not sure what you mean by hardware support.  The instruction set
> architecture needs to provide a breakpoint instruction.  A single-step
> mechanism is useful but not an absolute requirement - GDB can use
> software singlestep (although I suspect that code has bitrotten).
>
> Andrew
>

Thanks Andrew for your prompt replies. I was reading an article on "how gdb
works". This is a paragraph from that:

The Remote Serial Protocol's step command is a bit more challenging,
especially when the target processor doesn't provide a "trace bit" or
similar functionality (For example, Motorola 683xx processors contain the
ability to trap on instruction execution and/or changes in program flow;
this feature is controlled by the "trace enable" bits, T1 and T0, in the
processor's status register). In these cases, the only alternative is for
the stub to disassemble the instruction about to be executed so that it can
determine where the program is going to go next.

What I understood from this paragraph is that, if a target processor provide
"trace bit" kind of functionality, gdb developer's life is easier otherwise
he has to do some more work(disassembling of instruction). Am I right? Could
you please explain a little about "trace bit" or similar functionality? Is
it the breakpoint instruction, you mentioned about?

Regards
Mohanlal