Re: Listing probe alias resolution failures

[David Smith <dsmith@redhat.com>]

Frank Ch. Eigler wrote:
> Hi -
> 
> On Wed, May 16, 2007 at 03:17:55PM -0500, David Smith wrote:
>> [...]
>> Nope, I'm suggesting that:
>>    probe kernel.function("something_that_does_not_exist") ? {
>>       local1 = $arg1
>>       local2 = $arg2
>>       printf("%d %d\n", local1, local2)
>>    }
>> be accepted.
> 
> But it is already.
> 
> 
>> In other words, if we know a probe point doesn't exist, it shouldn't
>> matter what arguments it references. [...]
> 
> It doesn't.

Hmm, I see what you mean.  The following doesn't give an error for 
accessing $arg (although it does rightly complain that "no probes found").

# stap -p2 -e 'probe kernel.function("fche") ? { $arg1++ }'


Ah, I see something I missed before with the following:

# stap -p2 -e 'probe vm.mmap ? { printf("%p %d\n", address, length) }'

Here's the definition from tapset/memory.stp:

probe vm.mmap = kernel.function("do_mmap"), kernel.function("do_mmap2")? {
     address = $addr
     length = $len
}

I missed the fact that the first one isn't optional.  But, shouldn't 
making 'vm.mmap' optional basically make 'kernel.function("do_mmap")' 
optional?

-- 
David Smith
dsmith@redhat.com
Red Hat
http://www.redhat.com
256.217.0141 (direct)
256.837.0057 (fax)