Re: Debugging an early kernel problem (more MIPS trouble)

[David Holland <dholland-tech%netbsd.org@localhost>]

On Tue, Jul 05, 2016 at 02:00:35AM +0000, coypu%SDF.ORG@localhost wrote:
 > After failing to fix enough broken things with the interrupt code by
 > reading it, I wanted to try adding some code to let me know when the
 > interrupt level was changed.
 > 
 > I've attempted to add a couple of PRINTFs from <machine/asm.h>, but it
 > mostly fails to boot with the addition of this code.

Where have you put it? (Early in kernel startup, for example, there
are many things you can't do yet.)

 > gxemul gives these warnings:
 > [ warning: LOW reference: vaddr=0x00000000, exception TLBL, pc=0x00000000 <(no symbol)> ]
 > [ warning: LOW reference: vaddr=0x00000000, 000000 <(no symbol)> ]
 > [ warning: LOW reference: vaddr=0x00000000, exception TLBL, pc=0x00000000 <(no symbol)> ]
 > [ warning: LOW reference: vaddr=0x00000000, exception TLBL, pc=0x00000000 <(no symbol)> ]
 > 
 > I'm guessing it jumped somewhere it shouldn't have.

Yeah, jumped to null. I suspect if you patch gxemul to also print the
value of $ra (register 31) it will be somewhat more enlightening.

-- 
David A. Holland
dholland%netbsd.org@localhost