> The strange thing is that delay() calls "gettick()"
> (in isa/clock.c) which enables interrupts as a side
> effect. This means it shouldn't be called in device
> probe / attach at all (or stray interrupts will occur).
> This looks more like a bug to me.

I think so, too. 
We had a trouble (*1) which was caused by this.
Please fix this problem. (I'm sorry that I have not sent PR.)

(*1) Specific machines (Pentium-PRO 440FX chipset, serial console setting)
  hanged during boot, not always, but almost once per 20 times boot.
--
soda