3rd party package build system

[Chris Johns]

On 06/09/2017 19:56, Nicolas Tsiogkas wrote:
> I'm trying to integrate SOEM with RTEMS (https://devel.rtems.org/ticket/3120
> <https://devel.rtems.org/ticket/3120>)

Thank you for creating the ticket.

> As I am trying to create the appropriate bset and cfg files I noticed that all
> the packages built are based on autoconf to be built.

This reflects the nature of the packages we currently support and nothing more.

> SOEM on the other hand is only providing CMake as a build tool. 

This should be fine if the implementation in SOEM is ok.

> I have found instructions on using CMake with RTEMS
> (https://lists.rtems.org/pipermail/devel/2016-March/013800.html)
> 
> The question is if it would be more sensible to create a build environment for
> SOEM based on autotools or try to use CMake somehow?

I do not think there is a need. The upstream project has selected cmake and we
should respect that.

> I doubt that changing the build system will be easily accepted upstream.

Agreed.

The RSB scripts will invoke cmake so this bit is easy. The part you need to work
with the upstream project is getting a cross-complier build to work. How well
this works depends on how the cmake build scripts in the project are
implemented. Carefully constructed cmake build scripts and the judicious use of
the command line `-D` options can be used to configure and/or build the package.

I should warn you, use the cmake gui and tui tool at your own risk, if you step
in there you may never return as the same person.

The key file in the RSB is rtems-bsp.cfg [1]. It wraps a private package config
implementation that parses an installed BSP's build configuration [2] and
updates the internal RSB data [3].

I suggest you get the package to build from the command line for a BSP. This
will be the compiler name and cflags. What you end up with will be available in
the macros in rtems-bsp.cfg.

Have a look in the BSP installed .pc file for the flags to use, ie do a `find .
-name \*.pc` from the RTEMS installed prefix path.

My (publicly denied) cmake experience with RTEMS is configure header tests can
be fragile if there is cmake nesting.

Chris

[1] https://git.rtems.org/rtems-source-builder/tree/rtems/config/rtems-bsp.cfg
[2] https://git.rtems.org/rtems-source-builder/tree/rtems/config/rtems-bsp.cfg#n64
[3] https://git.rtems.org/rtems-source-builder/tree/rtems/config/rtems-bsp.cfg#n81