GNU Boot – BSD operating systems

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At the time of writing, there is no easily installable BSD operating system or distribution that is fully free. Because of that we cannot force contributors to the GNU Boot to install BSD operating systems to run tests, so we instead need voulunteers already running BSD systems to test booting such systems with GNU Boot.

At the time of writing, the most promising approach to fix this issue is to wait for HyperbolaBSD to produce something that can be downloaded so that any contributor could try it relatively easily.

As for the other BSD operating systems or distributions, The GNU project documents known freedom issues in various distributions that are not entierely free, and the same page also has a section on BSD operating systems.

Since GNU Boot is based on the last fully free version of Libreboot, and that Libreboot was capable of booting many BSD systems, booting BSD systems may still be possible in GNU Boot, but so far the GNU Boot project has not heard of anyone who reported that working.

# Video modes

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For BSD systems, it is desirable that you boot in text mode. ROM images with `txtmode` in the file name, on x86 systems, boot up with int10h text mode in use. This is the most “compatible” option, and BSD operating systems have excellent support for text-mode startup. Many of them also support kernel mode setting (KMS) nowadays, which you need if you want a graphical desktop on the X window system. The reason is that GNU Boot relies on projects that didn’t implement int10h VGA modes on x86 systems. However, basic video initialization is provided on all platforms (int10h (text mode), or high resolution coreboot framebuffer).

Combined with the use of SeaBIOS, BSD systems (and any other OS that can boot in text mode) should in theory just work, but they have not been recently tested with GNU Boot. If your BSD system supports kernel mode setting, it can set up a framebuffer without making use of int10h VGA modes. In this case, the driver (e.g. Intel video driver) will set modes directly, and implement its own framebuffer.

Booting with a coreboot framebuffer might also work well on most BSD systems, though that hasn’t been recently tested either. These ROM images have `corebootfb` in the filename, on recent GNU Boot releases. In this setup, you should make sure that your BSD system has a `corebootfb` driver (to make use of the coreboot framebuffer), but when switching to X, your video driver (e.g. Intel video driver) may already support kernel mode setting which means that the coreboot framebuffer will no longer be used at that point.

# Booting BSD

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GNU Boot currently provides the choice of GNU GRUB and/or SeaBIOS payload. You can use either payload, to try to boot BSD operating systems. If you do, please report your success or failure to the GNU Boot project through a bug report. See the “Documentation and/or testing” section in Helping GNU Boot page for more details on how to do that.

## SeaBIOS payload

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It is highly recommended that you use the SeaBIOS payload if you want to boot a BSD operating system or distribution. GNU Boot Images which start with the SeaBIOS payload are available in the latest GNU Boot release, for all the supported computers.

Most GNU Boot images with GNU GRUB also have SeaBIOS available in the boot menu, though it might not be the case for computers with a very small boot flash size (512 KiB) like the Intel D945GCLF. GNU GRUB, when compiled as a coreboot payload, runs on bare metal and it can boot any other coreboot payload if you use the `chainloader` command.

The way to use SeaBIOS is fairly self-explanatory. SeaBIOS functions the way you would expect on a typical computer. GNU Boot currently lacks any sort of documentation for SeaBIOS, but you can refer to their website: https://seabios.org/SeaBIOS

SeaBIOS was especially recommended by the Libreboot project when it was fully free for people doing an encrypted installation.

The Libreboot project also listed the fact that SeaBIOS was “basically more reliable” at least with BSD systems by giving the example of ZFS that was less reliable in GRUB and contrasting that with the fact that if a FreeBSD system booted in SeaBIOS, it would work just fine because the users would be using the bootloader provided by FreeBSD.

In addition, GNU boot may also remove support for booting encrypted BSD systems in the GRUB images it provides at some point, in order to make GRUB smaller to fit computer with a very small boot flash size (512 KiB) like the Intel D945GCLF, and unify the documentation, but also because it can’t currently test that due to the lack of fully free BSD systems that are easily installable.

## GNU GRUB payload

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GRUB can directly boot many BSD kernels, but according to the Libreboot at the time where it was still fully free, support for this was quite unreliable compared to its support for booting Linux kernels. However, you could use GRUB.

When you used GNU GRUB directly, in this way, the various BSD bootloaders were bypassed entirely.

The GNU Boot project has separate pages for each BSD system:

- How to install NetBSD on x86 GNU GRUB payload
- How to install OpenBSD on x86 GNU GRUB payload
- How to install FreeBSD on a x86 GNU GRUB payload

Markdown file for this page: https://gnu.org/software/gnuboot/web/docs/bsd/index.md