yabits: Fast and lightweight yet another UEFI implementation

yabits is a pure UEFI coreboot payload. Compared with TianoCore, it is fast and lightweight. yabits is based on the part of Minoca OS. It can run GRUB2, Linux, OpenBSD, and other UEFI applications. Tested on QEMU/KVM and Lenovo ThinkPad X230. It is still under the development and not ready for production.


The latest yabits is v0.0.1. This release is pre-release.

You can try yabits coreboot.rom on QEMU. Prepare UEFI-aware OS image. Run

$ qemu-system-x86_64 -drive if=pflash,format=raw,readonly,file=coreboot.rom -drive file=os.qcow2,if=none,id=sata -device ich9-ahci,id=ahci -device ide-drive,drive=sata,bus=ahci.0 -serial stdio -m 2G

GRUB2 booted from yabits

Build from Source

Step1 - Follow coreboot build instruction coreboot lesson 1 - Starting from scratch

Step2 - Clone yabits repository

$ git clone https://github.com/yabits/uefi.git
$ cd uefi

Step3 - Configure settings

$ make menuconfig

Step4 - Build yabits payload

$ make

Step5 - Configure coreboot

$ cd coreboot
$ make menuconfig
    select your favorite mainboard
    select 'Payload' menu
    select 'Add a Payload'
    select 'Payload path and filename'
    select 'uefi/build/build/uefi.elf'
    save config and exit
$ make


OpenBSD runs with yabits

OpenBSD runs with yabits

Boot time comparison on Lenovo ThinkPad X230. yabits vs default UEFI

Boot time comparison


Boot time and footprint

  Boot time (s) Footprint (MiB)
yabits 3.15 0.4
TianoCore 7.15 4.1

Other UEFI implementations

  Boot time Footprint Open source TianoCore free
yabits ✔️ ✔️ ✔️ ✔️
default ✖️ ✖️ ✖️ ✖️
TianoCore ✖️ ✖️ ✔️ ✖️
NERF ✔️ ✔️ ✔️ ✔️


yabits is lincesed under the terms of GNU General Public Lincese, version 3. See the headers of source code for more details.

This page is MIT license.