[RFC] RTEMS Waf Clang support

[Hesham Almatary]

On Mon, 16 Mar 2020 at 11:53, Sebastian Huber
<sebastian.huber at embedded-brains.de> wrote:
>
> On 16/03/2020 12:39, Hesham Almatary wrote:
>
> > Hi Sebastian,
> >
> > I have pushed a few commits to my repo to support building RTEMS with
> > Clang/LLVM for RISC-V. Here are the changes [1]. Since I'm still
> > learning about Waf and the build system, I'd appreciate your input.
> > Most importantly, I want to know what's the right way to set "target"
> > and "xlen" variables.
> >
> > [1] https://github.com/CTSRD-CHERI/rtems/compare/967b62464bf39602f8b0f2baf57617ad74c3643d...aa73f72b929856efdb41f9f8582263b5395a3276
>
> You need a new option, e.g.
>
> spec/build/cpukit/RTEMS-BUILD-CPUKIT-OPTXLEN.yml
>
> It should be enabled by clang and riscv:
>
> enabled-by:
>    and:
>    - clang
>    - riscv
>
> The option must be evaluated before the tool settings:
>
> order: -1000
>
Yes, I thought of that too. But I need to define XLEN to empty or
something for other architectures too since I use it in
RTEMS-BUILD-CPUKIT-OPTCLANG:

> - set-value: --target=${ARCH}${XLEN}-unknown-rtems${__RTEMS_MAJOR__}
> - substitute: null
> - env-append: ABI_FLAGS

How should each RISC-V BSP assign XLEN? I thought of a few ways:
1) to make each BSP yml file do it, or
2) to script it for RISC-V and extract it from the march value,
3) to assign it in a single file and, similar to how
RISC-V-BUILD-BSP-RISC-V-ABI currently works, assign it per variant.

>
>
>


-- 
Hesham