dtrace discuss - Apr 2008 - Help with some custom kernel sdt probes

I''m playing with FreeBSD''s port of DTrace

we''re adding some sdt probes to some kernel modules so we can time some
events

The probes load fine and they show up in dtrace -l, but I can''t manage
to access
 their arguments

here''s some snip of code

static void
em_intr(void *arg)
{
        struct adapter  *adapter = arg;
        struct ifnet    *ifp = adapter->ifp;
        uint32_t        reg_icr;

        SDT_INTR_PROBE(em, interrupt_start, adapter->dev, &em_intr, ifp,
adapter
, 0);


If I want to access some of the struct ifnet''s fields, like this:

sdt:::interrupt_end
{
        this->ifnet=(struct ifnet *)arg2;
        @[this->ifnet->if_xname]=quantize(timestamp-self->ts);
}



I get the following error:

dtrace: failed to compile script sdt-test2.d: line 13: operator -> cannot be
applied to a forward declaration: no struct ifnet definition is available

is there anything I''m missing to make the struct definition visible to
a
D script?

any help/suggestions would be greatly apreciated


Fer


     
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How recent is the FreeBSD source tree you are using?

You can try using cftdump on the kernel module and look for ifnet (to check that
there is CTF data for the structure).

Also note that the SDT implementation in FreeBSD differs from that in
OpenSolaris. On FreeBSD you can define your argument types where the probes are
declared. If you have a recent source tree, look at the SDT probes in (say)
src/sys/kern/kern_proc.c


--
This message posted from opensolaris.org