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[Bug runtime/6849] $$vars fails to display local variables on ppc64 system


------- Additional Comments From fche at redhat dot com  2008-08-19 13:27 -------

> I am not able see values of local variables in below scenarios either. 
> 
> =====================================
> [root@llm27lp1 src]# ./stap -e 'probe syscall.open { printf("%s \n", $$vars)}'
> filename=0x10020cf6 flags=0x880 mode=0x0 ret=?
> filename=0x10020cf6 flags=0x880 mode=0x0 ret=?
> filename=0x20006d30 flags=0x0 mode=0x1b6 ret=?
> filename=0x20006c50 flags=0x0 mode=0x1b6 ret=?

That makes sense since there are no local variables in scope at the moment
of function entry.  $$vars (or in this case $$locals) makes sense for
statement probes.

> ================================================
> [root@llm27lp1 src]# ./stap -e 'probe
> kernel.statement("sys_open@fs/open.c:1039") { printf("%s \n", $$vars)}'
> filename=0x10020cf6 flags=0x880 mode=0x0 ret=?
> filename=0x10020cf6 flags=0x880 mode=0x0 ret=?
> =====================================================

Try a few other line numbers, farther into the function.
This works OK for me.
   probe kernel.statement("sys_open@fs/open.c:*") { log($$vars) }
Try it for a longer function.

However, there are several known problems in placement of .statement()
probes right now, including bug #6687.


-- 


http://sourceware.org/bugzilla/show_bug.cgi?id=6849

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