Debugging with no serial port

Frank frannk_m1 at
Fri Aug 11 03:31:31 EST 2006

--- "Martin, Tim" <tim.martin at> wrote:

> This may be more of a question for GDB folks...but I'll post
> it here
> because it relates to embedded systems as well.
> I'm trying to validate some signal processing software on an
> embedded
> Virtex4 PowerPC 405.  Basically, the validation consists of
> calling
> functions and looking at their outputs.  Over time, there are
> several
> thousand numbers to look at, so manually looking at each
> number at a
> break point would be very time consuming (to put it mildly).
> The normal way I would go about doing this is to print out the
> data
> (e.g. to a serial port) and post-process the data somewhere
> else.  But
> on this particular target, I don't have a serial port.  So I
> thought
> about using GDB's breakpoint command list feature.  When the
> software
> has data it wants to print out, it calls a function
> "log_stuff".  I then
> set a breakpoint and command list in the "log_stuff" function,
> which
> writes out the variables I'm interested in checking out to a
> file named
> outputfile.bin.  E.g. the following command file does this:
> break log_stuff
> commands
>    silent
>    if (variable_logging_enabled)
>       append value outputfile.bin stuff1_variable
>       append value outputfile.bin stuff2_variable
>    end
>    cont
> end
> The problem I have with this approach is that GDB doesn't
> finish writing
> out everything before it continues executing the program, so a
> backlog
> develops.  So my first question would be, is there some GDB
> "flush" like
> command I could run before the cont statement?
> Second question would be - is there an easier way to
> accomplish what I'm
> trying to do, which is basically emulate a serial port with
> GDB.
> Tim

Use NetConsole or remotey log it with syslog...

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