[RTEMS Project] #3351: libbsd: Add support for conditional compilation of modules and compiler flags

[RTEMS trac]

#3351: libbsd: Add support for conditional compilation of modules and compiler
flags
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  Reporter:  Christian Mauderer  |      Owner:  Christian Mauderer
      Type:  enhancement         |     Status:  assigned
  Priority:  normal              |  Milestone:  Indefinite
 Component:  network/libbsd      |    Version:  5
  Severity:  normal              |   Keywords:  libbsd waf IPSec
Blocked By:                      |   Blocking:
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 I'll start in the next few days to add IPSec (client) support to the
 libbsd. Because IPSec is quite deeply integrated into some parts of the
 network stack it would have quite a performance impact on every system and
 not only the ones using IPSec. Therefore it is necessary to compile this
 support only conditionally.

 From my point of view that means that the build system needs two new
 capabilities:

 1. For IPSec the whole stack has to be compiled with certain defines. If I
 understood the FreeBSD build system correctly these defines would be set
 via generated header files. In RTEMS we have static files for that (like
 rtemsbsd/include/rtems/bsd/local/opt_inet6.h). I see two possibilities:
   a. Generate the headers depending on a configure option.
   b. Use empty headers like we already do it for a lot of options.
 Depending on a configure option then add a '-DSOME_OPT=1' to the modules
 that need it. That one would be my preferred way.

 2. IPSec adds a number of source files that most likely only work if the
 rest of the stack is compiled with the correct configuration. We already
 have modules in the libbsd.py. But currently they are added or removed by
 commenting the matching line in libbsd.py. My approach would be to make it
 possible to enable or disable the modules depending on a command line
 switch during configure.

 I'm open for any suggestions regarding better solutions.

--
Ticket URL: <http://devel.rtems.org/ticket/3351>
RTEMS Project <http://www.rtems.org/>
RTEMS Project