These configurations define the core Kconfig options you need for a kernel that supports the Go runtime, and thus u-root. See also: https://go.dev/wiki/MinimumRequirements

To build a small, flash-ready kernel, you would start from a minimal defconfig, something like:

make tinyconfig
cat amd64_config.txt >> .config
make oldconfig
make

Or some similar sequence (it has changed over the 15 years of this project).

The exact process is not important, what is important is that you need the options from these examples to make Go work. For one simple example, Go needs futex and that is not included in the tinyconfig default.

The files are in several sections, bracketed with comments. The first section includes what you need for Go; u-root init; serial console; early_printk; an initrd; devtmpfs (used by u-root init); ELF programs (yes, this is not included by default!); and /proc.

The second section is what you need so the io command will work.

The third is what you need to build a kernel that can kexec another. The fourth, for building a kernel that will itself be kexec'd.

Avoid the temptation to add to these files. They are intended to be the absolute smallest config that will still yield a working u-root initramfs. They have changed very little since we created them, meaning they can be used across a wide range of kernels.

Append these files to your tinyconfig.

• amd64_config.txt: for amd64/x86_64
• arm_config.txt: for arm
• generic_config.txt: Various architecture agnostic configs used by various integration tests.