The reference bootloader implementation for System Transparency.
The stboot bootloader can be used as an init program inside an initramfs and is designed to be combined with a Linux kernel to form a LinuxBoot distribution. It is closely related to the u-root project. On the one hand, stboot depends on some standard Linux tools packages provided by u-root, on the other hand, u-root is used to create an initramfs including stboot.
Make sure your Go version is >=1.13 && <1.16. Make sure your GOPATH is set up correctly. Although using modules, stboot still vendors dependencies to work smoothly with u-root. So if you are usually working with go modules enabled do the following in your working directory:
mkdir go
export GO111MODULE=off
export GOPATH=${PWD}/go
Download and install u-root and stboot:
go get github.com/u-root/u-root
go get system-transparency.org/stboot
Build an initramfs:
./go/bin/u-root -o initramfs.cpio -uinitcmd stboot github.com/u-root/u-root/cmds/core/{init,elvish,ls} system-transparency.org/stboot
There should be your brand new initramfs.cpio in you working directory.
Test your initramfs (assuming your OS kernel at /boot/vmlinuz):
qemu-system-x86_64 -kernel /boot/vmlinuz -nographic -append "console=ttyS0,115200 uroot.uinitargs='-debug'" -initrd initramfs.cpio -m 2048 --enable-kvm
You should see something like this:
[...]
[ 0.689686] Run /init as init process
2021/05/03 12:01:15 Welcome to u-root!
_
_ _ _ __ ___ ___ | |_
| | | |____| '__/ _ \ / _ \| __|
| |_| |____| | | (_) | (_) | |_
\__,_| |_| \___/ \___/ \__|
init: 2021/05/03 12:01:15 no modules found matching '/lib/modules/*.ko'
stboot:
_____ _______ _____ ____ ____________
/ ____|__ __| | _ \ / __ \ / __ \__ __|
| (___ | | | |_) | | | | | | | | |
\___ \ | | | _ <| | | | | | | | |
____) | | | | |_) | |__| | |__| | | |
|_____/ |_| |____/ \____/ \____/ |_|
As long as you can see the stboot banner, everything is fine. The program will exit with an error because of missing configuration data. See https://git.glasklar.is/system-transparency/core/system-transparency for details on how to set up System Transparency.