How to get anything useful out of kgdb?

Sean Bruno sbruno at ignoranthack.me
Sun May 10 02:00:09 UTC 2015


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>> 
>> I'm guessing that the place to change -O2 -> -O0 is in
>> kern.pre.mk ?
>> 
>> sean
> 
> No, it means you need to iescover DEBUG and how it affects
> optimization level :)
> 
> .if defined(DEBUG) _MINUS_O=       -O CTFFLAGS+=      -g .else ...
> 
> Say, I have 'makeoptions     DEBUG="-g -gdwarf-2"' in my kernel
> config file. -gdwarf-2 is probably not required anymore.

Indeed!  :-)

I was directed to go a slightly different way:

make.conf:
COPTFLAGS=-O0
CFLAGS=-O0


This makes unbootable kernels and they panic unless you defined the
following in your kernel config:
options		KSTACK_PAGES=6


sean
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