Hi guys,

I am a newbie of seL4 and I am trying to get some understanding of it. So, my first question is about the build system of seL4:

1. Why cmake has been taken to build it? I think there are at least two shortcomings about current build system based on CMakeLists.txt:

- Some build options were implied in the CMakeLists.txt. It's not easy to get a complete and comprehensive understanding of all the options. And some options depends on other options. Such as, ./init-build.sh -DPLATFORM=odroidc2 -DAARCH64=1 A new guys couldn't get a support list of PLATFORM option, and know AARCH64 is only for ARMv8 SoC easily.

- There are too much branches of platform or SoC Architectures. Such as: if(KernelArchARM) include_directories("include/arch/arm/armv/${KernelArmArmV}/") include_directories("include/arch/arm/armv/${KernelArmArmV}/${KernelWordSize}") endif() if(KernelArmMach STREQUAL "exynos") include_directories("include/plat/exynos_common/") endif() if(KernelArchRiscV) include_directories("include/arch/${KernelArch}/arch/${KernelWordSize}") include_directories("include/plat/${KernelPlatform}/plat/${KernelWordSize}") endif()

Linux Build System places the special build options and source files into the directory related with each architectures, and will generated a configure file (.config) during building. It's very good in my opinion.

In Android Build System, a given project building inherits a common build options set, and update these parts only related the given project. It's very good for integration.

And I want to know if there is a plan to update the build system or accept patches from volunteer?

2. I notice that, all kernel source files have been concatenated into a kernel_all.c, and compile the kernel_all.c. Is there some special reason for this step? It's a slight strange for me?

Anyway, I am a new guy. I just want to understand it and if I could provide something to change it. Any comments are appreciated.

Thanks, Jerry