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Re: Listing probe alias resolution failures


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)


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