Newbie Question: is there a rescue mode or shell access from loader?

Polytropon freebsd at
Fri Nov 11 06:44:31 UTC 2016

Re-including mailing list, hope that's okay.

On Thu, 10 Nov 2016 23:18:49 -0700, Mick mtn wrote:
> Thank you,
> I tried to interrupt the boot by repeatedly pressing the space bar as you
> recommended however it had no effect.
> The system continued the boot process and continued the loop
> (boot,panic,reboot).
> I can escape to the loader, it will allow me to give the unload command.
> It will not however allow me to boot into single user mode.

What happens when you issue the command "boot -s" at the loader
prompt? You should end up in single user mode, / mounted r/o, no
other partitions mounted, request for shell.

> I inserted the FreeBSD 11 R amd64 dvd that I used to initially install the
> system.  It will now not recognize the dvd.
> after holding the C on boot I do get a screen :
> 1.
> 2.
> select CD-ROM Boot Type :
> no keystroke seems to be seen by the system.

That doesn't look like typical FreeBSD behaviour. Sadly, using
Macbooks is in my case restricted to using Mac OS X, so I have
absolutely no experience booting them from "foreign" media or
installing FreeBSD on them... :-(

> I'm wondering if I may have a hardware failure of some sort.
> But the system was running prior to my last batch of print set-up edits per
> the Handbook section on printing.
> along with the inclusion of visa_load="yes" into boot/loader.conf.

Shouldn't that be vesa_load="YES"?

> While in loader prompt it does not find <mount>
> I've issued 'boot cdrom' and it reports "can't find kernel"
> Im perplexed.

What you see is fully correct. The loader does not have a "mount"
internal command. It's fairly restricted - because interactive
mounting is not part of what the loader does.

In order to boot from CD-ROM, you need to act at an earlier stage,
the "initial boot" program with the "boot:" prompt, where you can
set the boot device.

If you have passed that stage, you get the "Ok" prompt, the loader.
Here you can use "unload" for kernels and kernel modules, "boot -s"
to continue booting into single user mode, "boot -C" to boot from
CD-ROM, as well as rudimentary "ls" and "more" internal commands.

See table 12.1 here:

Detailed information can be found in "man 8 boot":

Magdeburg, Germany
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...

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