'unsigned long' triggers compiler to use 'long double' (which might be
	reasonable because there are no corresponding  machine op) and that option

Hm.  Why would using a 64-bit integer type force the use of 128-bit
floating point?  And what do you mean `no corresponding  machine op'?
there are both fxtod and fxtoq instructions, although the latter is
emulated.

	forces compiler to use just 'double' instead. That what I see from
	code generated. I don't know why 'hard-quad-float'd code doesn't work,

All quad instructions are emulated, so you need to debug the kernel
fpu emulation code.

	it doesn't seem wrong, I'm trying to debug it now. So if you got a chance
	to check that simple test out ...

Eduardo