Re: remote debugging

[Fernando Nasser <fnasser at cygnus dot com>]

Shaun Jackman wrote:
> 
> What is the preferred method for remote debugging?
> 
> I have an Atmel EB01, AT91M40400 processor (ARM7TDMI) which came with an
> Angel monitor in flash.
> Debugging with it is dead slow. Stepping through a few lines of code which
> occurs as fast as I can click in the simulator takes ~20 seconds with the
> Angel monitor. Also, I am unable to connect to the Angel monitor faster than
> 9600 (although I can go up to 38400 with the Arm Ltd. debugger).
> 

gdb 5.0 should be able to talk to RDI targets up to 115200.  Of course
it depends
on the board you have.  On a board I have with a StrongARM processor I
can talk
to Angel at 115200 but on the ARM Inc. $150 AEB board I can only connect
at 9600.

The protocol is very simple: gdb (actually, the code ARM gave us), using
9600 bauds,
proposes the speeds it can handle starting with the preferred one,
115200 of course,
and the board replies with the speed it can handle.  The AEB board
replies with 9600,
so gdb uses 9600 and things are slow as you say.

But there is not much we can do about this.  We cannot just ignore the
Angel monitor
reply because the board must switch to the appropriate speed after the
reply (and that
is the protocol, damn it!)


> I have a Jeeni on loan (JTAG Angel over ethernet) which allows me to debug
> as fast as the simulator, but they're bloody expensive! I'd prefer a serial
> or parallel solution if possible, only for cost reasons. (unless someone
> knows of a cheap ethernet device!)
> 
> Is serial-tether debugging necessarily as slow as the Angel monitor? Would
> Cygmon or the gdb-stub be better?
> 

Cygmon is nice.  It works fast at 115200 speed but it is only available
for some
boards.  You will have to check with your board manufacturer.


> My preferred development environment would be Linux, but I'm stuck in a
> dual-booting limbo right now until I can sort out my tool-chain problems.
> 

There was a problem, at some point, with the gdb RDI protocol (the one
used to
talk to Angel) on CygWin some time ago.  It works fine now, so if you
get a 
recent CygWin dll you should be able to use it on a Window box.

-- 
Fernando Nasser
Red Hat Canada Ltd.