This small wrapper is designed to help booting Mainline Linux on devices using Samsung S-Boot bootloader, especially Exynos7885 phones. It is currently capable of starting the linked Kernel image with a linked DTB, optionally waiting for a power button press before starting the kernel. The dtb given to the wrapper by S-Boot is ignored, but we currently use the ramdisk loaded in memory by S-Boot. The advantages are that we can modify the cmdline in the dtb without S-Boot interfering and we can plug in UART before the kernel boots after using Download mode to flash a boot.img
Do a simple make with optionally overriding the default variables.
These variables are:
CCPREFIX: Prefix to compiler commands. Default: "aarch64-linux-gnu-"
KERNEL_PATH: Path to the kernel image. Default: "kernel"
DTB_PATH: Path to the dtb. Default: "dtb"
CMDLINE: Command line passed to kernel. Default: "clk_ignore_unused"
POWER_KEY_BOOT: Only boot when the power key is pressed.
Example command:
make POWER_KEY_BOOT=1 CMDLINE="clk_ignore_unused fbcon=rotate:1" KERNEL_PATH=/path/to/kernel/arch/arm64/Image DTB_PATH=/path/to/kernel/arch/arm64/boot/dts/exynos/exynos7885-jackpotlte.dtb
Usage: The resulting "wrapped_kernel" can be used instead of a kernel in a boot.img to be flashed onto an S-Boot device. Providing a seperate dtb in the boot image is not neccessary.