Unofficial (Simplified) Libreboot Documentation
  • Home
  • Building from source/
  • External SPI flashing/
  • Freedom in Libreboot/
  • Maintainance manual/
  • Operating systems/
    • BSD systems
    • Linux-based systems/
  • Payloads/
  • Releases/
  • Targets/
  • UNCATEGORIZED/
Site license: GFDL v1.3 with disclaimer

BSD systems

Contents

  • Use SeaBIOS text mode payloads
  • Kernel mode setting
  • corebootfb
  • Graphical usage

This guide pertains to x86 Libreboot hosts. For ARM targets e.g. CrOS/ARM Chromebooks, you should refer to U-Boot documentation.

This guide documents some pitfalls when using BSD systems with Libreboot. For instructions on how to install and use BSD systems, refer to your BSD system’s documentation/handbook.

Use SeaBIOS text mode payloads

When flashing Libreboot, choose images with SeaBIOS, preferably ones with txtmode (since corebootfb is not guaranteed to work correctly).

GRUB can theoretically boot BSD kernels but it’s unreliable and poorly maintained. However, you may use GRUB to chainload SeaBIOS to boot BSDs.

It may be possible to use U-Boot x86, but this is largely untested and undocumented.

Kernel mode setting

Your BSD system must support kernel mode setting for your graphics device, if you want to use a graphical environment (such as Wayland or X11).

corebootfb

It is still recommended to use SeaBIOS in text mode, but: OpenBSD can work with SeaBIOS booting in a coreboot framebuffer with SeaVGABIOS when on a MBR partitioning table. In Libreboot ROM images, this would be SeaBIOS images with corebootfb in the file name.

FreeBSD corebootfb is broken.

Graphical usage

One important peculiarity of most Libreboot systems is that VGA mode support exists if booting with corebootfb (coreboot’s own framebuffer — direct memory framebuffer with many quirks, not technically a VGA mode) and the SeaVGABIOS option ROM is used in the SeaBIOS payload; however, the ability to switch modes is absent, which means that coreboot will stay in framebuffer or INT10H text mode (whichever is set), unless KMS is used to change the mode.

The BSD bootloaders on x86 BIOS systems, typically expect text mode startup. It is not possible to set the console to higher VGA modes on most coreboot systems with native video initialisation used. If you see any BSD documentation pertaining to VESA modes, ignore it entirely unless you’re using the proprietary VGA ROM for your device.

This would otherwise mean no X11/Wayland: If you start in corebootfb mode with SeaVGABIOS, you won’t get a display in BSD bootloaders, and if you boot in text mode, you can’t set VESA modes from BSD. However, At least OpenBSD and FreeBSD (possibly others) all have excellent KMS (kernel mode setting) support nowadays; and it’s often loaded by default. kernel set modes directly. It is based on KMS drivers that the BSD projects ported over from the Linux kernel. With this, you can use X11/Wayland.

For example: on FreeBSD, you can install graphics/drm-kmod as a package or from ports (if the package causes glitches, try building from ports, as occasionally the package will try to install modules for incompatible kernel versions), and (for Intel GPUs) do sysrc kld_list+="i915kms". Make sure /etc/rc.conf has kld_list="i915kms". On FreeBSD it is also recommended that you switch to KMS on the console/TTY; add kern.vty=vt /boot/loader.conf so that you can still use the console after terminating Xorg.

You should not rely on the above instruction (for FreeBSD), because the exact step might change, and it does not go into full detail either. Refer to the documentation provided by your system, to know how KMS is configured.

tl;dr: Just try it out to see if KMS is loaded by default. If not, look up how to enable KMS.