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

[coypu%SDF.ORG@localhost]

On Tue, Jul 05, 2016 at 03:52:21AM +0000, David Holland wrote:
> 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

Just putting one in splraise in spl.S will do it, many of the places
where I'd want to print a message are problematic.
Even attempting to do things the hard way and trying to save to an
arbitrary point in memory is not working out, it won't boot.
What does work?

Thanks.