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From: Gerd Hoffmann <kraxel@redhat.com>
Date: Thu, 25 Sep 2014 16:08:13 +0200
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Subject: Re: [Qemu-devel] [PATCH] ohci: Split long traces to smaller ones
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To: Alexey Kardashevskiy <aik@ozlabs.ru>
Cc: qemu-devel@nongnu.org

On Do, 2014-09-25 at 19:38 +1000, Alexey Kardashevskiy wrote:
> On 09/25/2014 06:09 PM, Gerd Hoffmann wrote:
> > On Do, 2014-09-25 at 10:16 +1000, Alexey Kardashevskiy wrote:
> >> Recent traces rework introduced 2 tracepoints with 13 and 20
> >> arguments. When dtrace backend is selected
> >> (--enable-trace-backend=dtrace), compile fails as
> >> sys/sdt.h defines DTRACE_PROBE up to DTRACE_PROBE12 only.
> >>
> >> This splits long tracepoints.
> > 
> > Can you also change the tracing-enabled check to use '#ifndef
> > CONFIG_TRACE_NOP' as suggested by Stefan please?
> 
> Nope :( As I said in that thread, I am not familiar with "dtrace" - are
> traces configurable with it? With --enable-trace-backend=dtrace,
> trace_event_get_state is not defined so CONFIG_TRACE_NOP is not 100% equal
> replacement.

Ah, ok.

IIRC with dtrace / systemtap you enable the trace point by other means
than qemu monitor commands, which is probably the reason
trace_event_get_state isn't there.

So trying to skip the calls with tracing turned off isn't going to fly
as qemu doesn't know in the first place whenever a tracepoint is enabled
or not.

cheers,
  Gerd