Trace status update.

[Chris Johns]

Hi,

I have added some pages to the developer's wiki:

  https://devel.rtems.org/wiki/Developer/Tracing

and I am slowly adding more detail. I intend to update the Trace Linker 
with more detail on the configuration files.

I have just updated the trace linker to support:

  1. Option sections.
  2. Names,
  3. Enables, and
  4. Triggers

The option sections allow you to put custom options into configuration 
files. For example:

  [my-options]
  dump-on-error = true
  ;
  ; Tools, linker for linking C++
  ;
  prefix = /opt/work/rtems/4.11
  ld = arm-rtems4.11-g++
  rtems-bsp = arm/xilinx_zynq_zc706
  rtems-path = /opt/work/my/rtems/4.11
  cflags = -I/my/private/path
  ;
  ; Generator options.
  ;
  gen-enables = enable
  gen-triggers = enable

Names is adding the names of all trace functions to a 'const char*' 
array indexed by the function index.

Enables is a bitmap array of uint32_t where each bit is indexed by the 
trace function index. The bit set means tracing is enabled for this 
function.

Triggers is a bitmap array of uint32_t where each bit is indexed by the 
trace function index. The bit set means trigger tracing. I have only 
defined a single bit at this point in time. We should actually have more 
so we can define entry and exit or both trigger states.

These changes allow a standard alone buffered trace support as well as 
move us a bit closer to integrating to the capture engine.

Chris