How to get anything useful out of kgdb?

[Sean Bruno]

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On 05/09/15 11:09, Jeff Meegan wrote:
> You could try -O0, but also if you just care about txr, go up to
> frame 12 where txr initialized to the context arg to em_handle_tx()
> and print it out there.
> 
> —j

I'm guessing that the place to change -O2 -> -O0 is in kern.pre.mk ?

sean

> 
>> On May 9, 2015, at 11:02 AM, Sean Bruno <sbruno at ignoranthack.me>
>> wrote:
>> 
> On 05/09/15 10:20, Sean Bruno wrote:
>>>> 
>>>> tl;dr  What are the kernel config options to get good output
>>>> of kgdb?
>>>> 
>>>> 
>>>> I'm trying to get the ability to debug and display internal 
>>>> variables, as one does, with kgdb.  I'm *must* be doing this
>>>> wrong as I cannot get any useful output from accessing
>>>> variables that were JUST accessed in order to invoke a
>>>> panic() that I have inserted.  This is a GENERIC kernel
>>>> without INVARIANTS and without WITNESS:
>>>> 
>>>> https://people.freebsd.org/~sbruno/wtf_kgdb.txt
>>>> 
>>>> I seem to have debug enabled and am able to browse source,
>>>> but I obviously haven't compiled correctly as things are
>>>> optimized out.
>>>> 
> 
> Just to see what the arguments to make are when building, I
> touched if_em.c and did a NOCLEAN rebuild.
> 
> What I see is this: 
> https://people.freebsd.org/~sbruno/wtf_make.txt
> 
> Should -02 and -g do anything useful here when compiling?  Do I
> need to drop the optimization flags?
> 
> sean
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> 
> 
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