description.txt

Description of YALDA project structure

YALDA project provides tools for build Linux image alongside with
different components required for running and debugging kernel modules.
It support build of the following components:
    - kernel
    - rootfs
    - busybox
    - whistle (not build )

The build steps of the components provided by "YALDA/yalda" script.

1. Configuration of YALDA project
- Run "make menuconfig". Kconfig files for YALDA configuration: "YALDA/config/kconf"
- Configure environment according to requirements. Save configuration in .config
  file at: "YALDA/.config"

2. Configuration of components
- Environment variables will be created for the components: kernel, busybox, whistle, rootfs.
- "YALDA/yalda" depends on:
    -- "YALDA/scripts/env"
- "YALDA/scripts/env" depends on:
    -- "YALDA/scripts/utils"
    -- "YALDA/config/default"
    -- "YALDA/.config"
- "YALDA/yalda" processing based on parameters exported in "YALDA/scripts/env".
- "YALDA/scripts/env" setup environment variables general for all components.
- "YALDA/scripts/env" setup environment variables by the following rule:
    -- If variable is not set: set variable to value of "YALDA/.config" variable.
    -- If "YALDA/.config" variable was not set: set variable to value of "YALDA/config/default" variable.
- For each component "YALDA/scripts/env" setup environment variables from "YALDA/scripts/<component_name>/env".
- Preparation of component source follows the rule:
    -- If "YALDA/.config":KERNEL_FROM_GIT=y: sources get from git and stored in "YALDA/components/<component_name>".
    -- Else: expect that component source exist at "YALDA/components/<component_name>".

2.2. Prepare component
- For each component "YALDA/scripts/env" setup component actions from "YALDA/scripts/<component_name>/build".

2.2.1. Prepare component: kernel
- Configure kernel:
    -- If "YALDA/.config":KERNEL_DEFCONFIG=y:
        -- Merge "YALDA/config/kernel/kernel.config.common" -> "YALDA/components/kernel/.config".
        -- Merge "YALDA/config/arch/<arch>/kernel.config" -> "YALDA/components/kernel/.config".
    -- Else: Copy existed kernel config "YALDA/config/kernel/kernel.config.last" to "YALDA/components/kernel/.config".
    -- Copy "YALDA/components/kernel/.config" to "YALDA/config/kernel/kernel.config.last".
- Patch kernel:
    -- Apply patches in "YALDA/patches/kernel" to "YALDA/components/kernel".
- Build kernel:
    -- If "YALDA/.config":ARCH_ARM=y: build devicetree.
    -- Create directory "YALDA/out/kernel".
    -- Create build output in "YALDA/components/kernel".
- Install kernel:
    -- If "YALDA/.config":ARCH_ARM=y: copy devicetree to "YALDA/out/kernel".
    -- If "YALDA/.config":KERNEL_FROM_HOST=y": copy host kernel to "YALDA/out/kernel".
    -- Else: copy image, vmlinux, gdb scripts from "YALDA/components/kernel" to "YALDA/out/kernel".

2.2.2. Prepare component: busybox
- Configure busybox:
    -- Configure with file from "YALDA/config/busybox/busybox.config".
- Patch busybox:
    -- Apply patches in "YALDA/patches/busybox" to "YALDA/components/busybox".
- Build busybox:
    -- Create build output in "YALDA/components/busybox".
- Install busybox:
    -- Copy build output from "YALDA/components/busybox" to "YALDA/out/busybox".

2.2.3. Prepare component: rootfs
- Install rootfs:
    -- Copy build result from "YALDA/components/rootfs",
       "YALDA/out/kernel", "YALDA/out/busybox" to "YALDA/out/rootfs"


YALDA Kconfig tree (arm, all flags enabled):

Target (arm)  --->
    ( ) x86
    (X) arm
[*] 64 bit
(arm-linux-gnueabihf-) CROSS_COMPILE

build
    [*] Kernel  --->
        (./components/kernel) Work directory
            Kernel source (dir)  --->
                ( ) git
                (X) dir
        [*] configure
                method (defconfig)  --->
                    (X) defconfig
                    ( ) manual
        (bcm2835_defconfig) defconfig
        [*] patch
        (./patches/kernel) patches dir
    [*] Busybox  --->
        (./components/busybox) Work directory
            Source (git)  --->
                (X) git
                ( ) dir
        (./config/busybox/busybox.config) defconfig
        -*- configure
        [*] Patch
        (./patches/busybox) directory
    [*] build  --->
        (./components/rootfs) Work directory
        (./initrd.cpio.gz) output
        () additional directory
    Addons
        [*] Whistle  --->
            (./components/whistle/subcomponents/kernel_module) Work directory
run
    [*] early debug
    [*] host kernel
    (./out/kernel/boot/zImage) kernel
    (./out/kernel/vmlinux) vmlinux
    (./initrd.cpio.gz) initrd
    (rdinit=/sbin/init rw earlyprintk loglevel=8 console=ttyAMA0) cmdline
    --> qemu
        (out/kernel/dtb/bcm2836-rpi-2-b.dtb) dtb
        (2) memory (GB)
    --> gdb
        (./scripts/gdb/kernel_gdb_script) script
        (-tui -nx -iex set auto-load safe-path /) parameters
[*] Verbose output