Re: trace_printk() support in trace-cmd

[Avi Kivity <avi@redhat.com>]

On 11/15/2010 07:11 PM, Steven Rostedt wrote:
> On Mon, 2010-11-15 at 19:09 +0200, Avi Kivity wrote:
> >  trace-cmd doesn't like trace_printk():
> >
> >  <...>-23775 [000] 26343.288803: kvm_emulate_insn:     0:f14e9: rep insb
> >  <...>-23775 [000] 26343.288804: bprint:               x86_emulate_insn :
> >  (NO FORMAT FOUND at ffffffffa0131460)
> >
> >  <...>-23775 [000] 26343.288807: bprint:               x86_emulate_insn :
> >  (NO FORMAT FOUND at ffffffffa0131460)
> >
> >  any chance to get it to work with custom printks?
> >
> >  I guess I should use 'perf probe' instead.
> >
>
> Which kernel are you using, and/or which trace-cmd? It works fine for
> me. But there has been bugs with older kernels and older trace-cmds.

kernel 2.6.37-rc1+, I think latest trace-cmd; will retry.

Meanwhile 'perf probe' grumbles on anonymous unions:

> src(tyep:operand) has no member val.
> Failed to find 'ctxt' in this function.
>   Error: Failed to add events. (-22)

For

--add 'insb=arch/x86/kvm/emulate.c:3369 insn=ctxt->decode.b 
bytes=ctxt->decode.dst.bytes port=ctxt->decode.src.val 
cx=ctxt->decode.regs[1] di=ctxt->decode.regs[7] 
addr=ctxt->decode.dst.mem.addr cpos=ctxt->decode.io_read.pos 
cend=ctxt->decode.io_read.end'

(ctxt->decode.src.val is a member of an anonymous union in 
ctxt->decode.src, which is of type 'struct operand')

-- 
error compiling committee.c: too many arguments to function