[dtrace-discuss] How to print kernel global variable.

[Brian Utterback]

Hmm. IS there anyway to tell dtrace what the type is? Something like the 
'-t' flag to print in mdb?
Maybe 'int64_t timedelta' perhaps?

Adam Leventhal wrote:
> Hi Brian,
>
> The problem is that DTrace won't let you use a kernel variable if it can't
> infer the type. Since 'timedelta' is defined in an assembly file, we don't
> have CTF data. Feel free to file a bug -- this should be made to work.
>
> I was able to trace 'timedelta' by getting its address using mdb and plugging
> that into my D script:
>
> # echo timedelta=K | mdb -k
>                 fffffffffbc02930 
> # dtrace -n BEGIN'{ trace(*(int64_t *)0xfffffffffbc02930ULL); }'
> dtrace: description 'BEGIN' matched 1 probe
> CPU     ID                    FUNCTION:NAME
>   1      1                           :BEGIN                 0
>
> Adam
>
> On Tue, Feb 13, 2007 at 03:05:03PM -0500, Brian Utterback wrote:
>   
>> I am doing some testing on the adjtime syscall, and I want to
>> dump out the value of the kernel variable "timedelta", and I
>> am failing at it. Some of my attempts got "Module is no longer
>> loaded" and some got "Symbol table entry is not a data object"
>>
>> I found some info that dtrace can print out kernel global
>> variable, so what am I missing here?
>> -- 
>> blu
>>
>> "Remember 'A Thousand Points of Light'? With a network, we now have
>> a thousand points of failure."
>> ----------------------------------------------------------------------
>> Brian Utterback - Solaris RPE, Sun Microsystems, Inc.
>> Ph:877-259-7345, Em:brian.utterback-at-ess-you-enn-dot-kom
>> _______________________________________________
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>>     
>
>