samsungexynos7870/android_kernel_samsung_exynos7870 — reverse-engineered prompt

Build me a clean Android Linux kernel source project for Samsung devices using the Exynos 7870 chip. I want to be able to clone it, run one build script, choose or use the right default config, and get a kernel image and modules that could be packaged for an Android device.

Keep it close to a normal Linux 3.x kernel layout with drivers, arch, file systems, networking, sound, security, documentation, and the usual make config options. Include the GPL license files and a simple README that explains how to install the source, configure it with menuconfig or oldconfig, build in a separate output folder, and handle common build problems.

Please make the build script friendly for someone who is not a kernel expert. It should check for missing tools, print clear errors, and not silently fail. Avoid changing device behavior beyond making the kernel compile cleanly. Look up current Android kernel build notes online if you need to.