> Is the DUOTEST kernel really boot on other Duos and PBs?

It should also be tested on other systems.  Especially the tt0 -> tt1
changes in locore.s.  I seem to recall that those changes caused
problems for other people.

> What to do with locore.s ? I have no idea with assembly language.

I would probably make a global integer flag variable:
int mac68k_use_tt1 = 0;

And then in locore.s:
		.globl	_mac68k_use_tt1

		...
		tstl	_mac68k_use_tt1
		beq	Lusett0_1
		.dword	/* use tt1 */
		bra	Ldonett0_1
Lusett0_1:	.dword	/* use tt0 */
Ldonett0_1:	...

> What is the meaning of the line
> "if ((via_reg(VIA1, vIFR) & 0x10) == 0x10)" in pm_direct.c .

If VIA1's interrupt flag register has bit 4 (0x10) set, then an
interrupt is being flagged on that interrupt line.  That's probably a
"character ready" interrupt (although I have not looked at the code
to be sure).

-allen