kernel doesn't boot when is built with ukbd/ums

Hi.

Today I noticed that when kernel has build-in ums and ukbd support,
it stops booting with the last seen messages (transcribed):
...
uart0: [FILTER]
atkbdc0: <Keyboard controller (i8042)> port 0x60,0x64 irq1 on acpi0
[stops here]
...

It boots fine if kernel is built without ums and ukbd devices (and
they loaded as modules). And I see in this case.
...
atrtc0: <AT realtime clock> port 0x70-0x71 irq 8 on acpi0
uart0: <16550 or compatible> port 0x3f8-0x3ff irq 4 flags 0x10 on acpi0
uart0: [FILTER]
atkbdc0: <Keyboard controller (i8042)> port 0x60,0x64 irq 1 on acpi0
atkbd0: <AT Keyboard> irq 1 on atkbdc0
kbd0 at atkbd0
atkbd0: [GIANT-LOCKED]
atkbd0: [ITHREAD]
cpu0: <ACPI CPU> on acpi0
...

In both cases I have in loader.conf:

ums_load="YES"
ukbd_load="YES"

I would jump in ddb to see what's going on, but my USB keyboard begin to work
only if I replug it close to the multiuser. Hence I can't.

-- 
wbr,
pluknet