devd started with single-user mode?

Polytropon freebsd at
Mon Mar 21 11:11:36 UTC 2011

On Mon, 21 Mar 2011 11:45:06 +0100, David Demelier <demelier.david at> wrote:
> By the way why is kbdmux needed for an usb keyboard? Should not be 
> managed by ukbd only?
> I don't understand .. But thanks for the patch.

Basically, the kbdmux option "wires keyboards in parallel", so
you can use both keyboards (assume they are physically present)
at the same time, like "one keyboard for each hand". If this
option was not present, you would have to use "kbdcontrol -k"
to switch from one keyboard (the currently active one) to the
other (not usable). Problems may occur if your mainboard does
provide an AT style keyboard (usually with PS/2 connector) as
atkbdc0 and adkbd0 (controller and keyboard) even if there is
no physical keyboard attached. This would then usually become
the primary keyboard. A USB keyboard, detected later on as
ukbd0, would not automatically be activated (or switched over
to by a "kbdcontrol -k" command issued by devd) and can therefore
not be used, even if physically present (in opposite to the
"phantom" keyboard atkbd0). The kbdmux option makes _all_
keyboards available for input (without using "kbdcontrol -k"
and without dependency of devd) so the USB keyboard will be
used, the AT "phantom" keyboard will be ignored (which is good
when it's not even present).

So basically, kbdmux means "use all of them", while its absence
means "use this or that".

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

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