Command line arguments

[Steve Strobel]

At 02:08 PM 10/14/2004 +0200, you wrote:
>Hello Ed
>
>Thanks for your reply.
>
>On Thu, Oct 14, 2004 at 07:30:26AM -0400, Ed Sutter wrote:
>> Lars,
>> I beleive this is boot loader specific.  At the time of command
>> line entry, the boot loader is still the active program, so it 
>> must provide the ability to deal with arguments.  In MicroMonitor,
>> this is very easy to do and pretty much independent of the CPU/RTOS.
>> 
>> Command line arguments established when the application starts up
>> are stored in the monitor's environment, then through a monitor
>> API call, they can be retrieved from anywhere in application
>> space (assuming the application doesn't disallow access to the
>> monitor's API because of MMU-based protection).
>> 
>> In most uMon-based applications, this API call is made prior to main()
>> so that argc/argv are populated just like a normal program; however,
>> this isn't a requirement.
>
>Yes, I know of the monConnect and mon_getargv calls to uMon, but my
>problem is not getting the arguments from the boot loader. My problem is
>to get the arguments from the bootcard function into my task.
>
>Thanks
>Lars Munch


We are using uMon, but ran into the same problem.  We retrieved the command line arguments in rtems_main, but didn't have a clean way to get them into the thread that needed them.  We probably could have waited to retrieve them from uMon until we were in that thread, but we used a couple of global variables instead.  Some of the relevant code follows.  Please let me know if you need more information about what we did, or if you have a cleaner way of doing it.

Steve

P.S.  Should this kind of thing go in the wiki?  If so, where?


// don't know how to pass argc and argv through the tread starting 
// mechanism, so using globals to bypass it
int global_argc = 0;
char **global_argv = 0;

// this function exists only to get the argument and return values right
rtems_task rtems_call_to_rlc_main(rtems_task_argument argument)
{
  // don't know how to pass argc and argv through the tread starting 
  // mechanism, so using globals to bypass it
  rlc_main( global_argc, global_argv );
}

// from example in c_user.pdf
void start_rlc_in_thread(int argc, char **argv)
{
  rtems_id tid;
  rtems_name name = rtems_build_name( 'R', 'L', 'C', 'T' ); // RLC Task

  // don't know how to pass argc and argv through the tread starting 
  // mechanism, so using globals to bypass it
  global_argc = argc;
  global_argv = argv;

  rtems_status_code status = rtems_task_create( name, 100,
    RTEMS_MINIMUM_STACK_SIZE * 2,    // Since we are allocating more than 
                                     //the minimum stack size, we need to 
                                     // account for it by defining 
                                     // "CONFIGURE_EXTRA_TASK_STACKS" to the 
                                     // appropriate value in rtemscfg.h
    RTEMS_PREEMPT | RTEMS_TIMESLICE, 
    RTEMS_FLOATING_POINT | RTEMS_LOCAL, &tid );

  if ( status != RTEMS_SUCCESSFUL ) 
  {
    debug_printf( "rtems_task_create failed with status of %d.\n", status );
    exit( 1 );
  }
  status = rtems_task_start( tid, rtems_call_to_rlc_main, 0 );
  if ( status != RTEMS_SUCCESSFUL ) 
  {
    debug_printf( "rtems_task_start failed with status of %d.\n", status );
    exit( 1 );
  }
}


---
Steve Strobel
Link Communications, Inc.
1035 Cerise Rd
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(406) 245-5002 ext 102
(406) 245-4889 (fax)
WWW: http://www.link-comm.com
MailTo:steve at link-comm.com