Separate platform dependent code from core

[antoinealb]

We need to separate platform specific from reusable code. See #22. The rationale is that we will reuse the bootloader for various boards, not only motor controller.

My suggestion is to place all board specific code into a platform/ folder and code that can be reused between some but not all platforms in an arch/ or port/ folder.

From a continuous integration point of view this is better than having a lot of different repositories because we can setup Travis to rebuild all ports on changes to core. It is also easier to manage development if it is somewhat centralized.

What do you think ?

[msplr]

Alternative: How about git branches for different boards? Thought, I'm ok with your suggestion. Maybe not such a complicated folder structure, since it really is not so much code.

[antoinealb]

I don't like git branches to manage different build configurations because it is easy for them to diverge and need very strong discipline to be regularly merged / rebased.

[msplr]

I see your point. The advantage of branches is, that the repo is not filled with every existing port. Though, like I said: I'm ok with your suggestion, if we can keep it tidy.

[pierluca]

Just throwing in my 2 cents. Strongly with @antoinealb here. Besides the risk of diverging with branches, I believe that ports are an integral part of the code base, not a version of said code. Conceptually, I can't see them as branches.

[msplr]

Here a proposal for the folder structure:

platform/
├── common
│   ├── armv7-m
│   │   └── boot.s
│   └── stm32f3
│       ├── can_interface.c
│       └── flash_writer.c
└── cvra-motorboard-v1
    ├── include.mk
    └── main.c

To build a specific target, the Makefile in the project root includes the platform/target/include.mk to get the needed C sources an include directories.

[Stapelzeiger]

Rename common to MCU? And I' not sure but i think the packager can build multiple targets, so the cvra-motorboard should contain a package.yml instead of the include.mk.

[antoinealb]

Could you show an example of what include.mk contains ? Is it a jinja template for packager ?

[msplr]

@antoinealb: It just adds the sources and include paths to the Makefile's variables. Though the solution proposed by @Stapelzeiger is probably better. Then we can create a packager-target for every platform.

[msplr]

How should the build system work for different targets? A different Makefile for each platform or one Makefile with different make targets? I think it would be nice if we can build all target platforms and run the test with one command.

[antoinealb]

I would say one makefile per platform and one "root" makefile which just run make into the different folders.

[antoinealb]

@nuft Do you think your plaftform dependent code will be ready for merge soon ?

[msplr]

I'm working on it. I'll make a pull request somewhen in the next few days.