[CMake] [Dev] CMake 2.5 tool chain support example

[Trevor Kellaway]

Alex,

> > Attached is an example set of scripts for adding tool chain support 
> > for Freescale HC12 embedded 16-bit microcontroller. This is 
> intended 
> > as a demonstration to others for how to add additional tool chain 
> > support (see the ReadMe.txt in the ZIP).
> >
> 
> Thanks for your efforts, this looks really good !
> But before publishing this as tutorial, please wait until 
> everything is tested a bit more and we found the final form 
> for everything.

No problem, when everything is stable I was intending to create a Wiki
page for this, with extracts from this example.


> Some questions/notes:
> You are using HC12_CORE. I'm still wondering whether 
> standardizing on CMAKE_SYSTEM_PROCESSOR (which already 
> exists) would be a good idea to use for this. 

As Kishore said the problem is that for microcontrollers there is
normally a family and a specific processor. In this case "HC12" is the
family, the actual processor is a "MC9S12DP512".


> Maybe the system type should be set to "Generic". Then cmake 
> could automatically try to load ${CMAKE_SYSTEM_NAME}.cmake # 
> does probably nothing ${CMAKE_SYSTEM_NAME}-${CMAKE_C_COMPILER}.cmake
> # "Generic-hc12.cmake", sets compiler rules and 
> ${CMAKE_SYSTEM_NAME}-${CMAKE_C_COMPILER}-${CMAKE_SYSTEM_PROCES
> SOR}.cmake
> # sets the flags for the processor
> 
> What do you think about this ?

I don't see any difference between
"${CMAKE_SYSTEM_NAME}-${CMAKE_C_COMPILER}.cmake" and
"${CMAKE_SYSTEM_NAME}-${CMAKE_C_COMPILER}-${CMAKE_SYSTEM_PROCESSOR}.cmak
e" as they are both for the same family and use the same settings.

${CMAKE_C_COMPILER} isn't really "HC12", it is actually "chc12.exe", so
this could be misleading.

I can see merit in your approach, for my core type, but I also need some
way of easily embedding the memory model. I'll think about this some
more, as none of our proposals feel right yet.


> Why are CMAKE_C_COMPILER, CMAKE_CXX_COMPILER not in the 
> toolchain file ? 
> This would then automatically disable also 
> CMAKE_SKIP_ASSEMBLY_SOURCE_RULES, 
> CMAKE_SKIP_PREPROCESSED_SOURCE_RULES (which you do currently 
> manually).

Err, because I didn't know this! <g>


> I'm not sure about the -opt.cmake file. Can't this simply be 
> done in the CMakeLists.txt ?

It could, but I want to be able to move source code to another processor
environment without editing its CMakeLists.txt, having the "-opt" allows
me to do this, it also makes importing existing projects easier.

 - TrevK