Installation 'halts' at boot after initialising UEFI framebuffer

Michael Neumann mneumann at
Mon Jan 7 07:37:56 PST 2019

On Mon, Jan 07, 2019 at 02:01:50PM +0000, cbz wrote:
> Hi -
> Currently when I try to use the installation media the boot process appears
> to halt right after initialising the EFI framebuffer.  The messages I get
> are identical to the ones here, except that the resolution is different.  I
> can screenshot if there is sufficient interest:
> Looking here, it appears that this was a problem with FreeBSD in the past,
> and possibly one that was later fixed (there are various references on the
> web to alternatively using the 'gop' command in the boot loader, or setting
> variables like kern.vty):
> Has anyone seen anything similar with dragonfly and been able to fix it ?
> Switching back to legacy (non-UEFI) mode is not an option in this case as
> the motherboard doesn't support this.  Are there any boot
> variables/settings I can change to use a non EFI framebuffer console?
> I quoted 'halts' in the subject, as my belief is that the installer process
> actually works, it's just that the framebuffer device isn't working
> correctly (as per the first link above).


Yes, I had a similar issue. I think what you are seeing is similar to

It took me many nights to hack debug code into the boot loader and early
kernel startup (hard to debug without serial console or any screen
display :D) to figure out that it is actually booting, but that the
framebuffer is not correctly initialized, so you just don't see anything
on screen (it might kernel panic later on... but it definitively starts
the kernel and probes the devices).

I have a patch below that works for me. You need to apply it to /usr/src
( cd /usr/src && patch -p1 < patch-fb-machdep.c) recompile and reinstall
the kernel. Let us know if you have trouble with the patching procedure.

You need to set the loader tunable "sc.probe_early=1" before booting in
the boot loader.

Would be great if you could open up a bug report on with your bug description.

BTW, when I boot FreeBSD with the same Laptop, I actually see something
on the screen, but it is totally scrambled.



Michael Neumann
NTECS Consulting

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