Re: [Qemu-devel] [RFC][PATCH v3 03/21] virtproxy: add debug functions for virtproxy core

[Michael Roth]

On 11/18/2010 05:43 AM, Stefan Hajnoczi wrote:
> On Thu, Nov 18, 2010 at 11:09 AM, Jes Sorensen<address@hidden>  wrote:
> > On 11/16/10 02:15, Michael Roth wrote:
> > > Signed-off-by: Michael Roth<address@hidden>
> > > ---
> > >   virtproxy.c |   17 +++++++++++++++++
> > >   1 files changed, 17 insertions(+), 0 deletions(-)
> > >
> > > diff --git a/virtproxy.c b/virtproxy.c
> > > index 8f18d83..3686c77 100644
> > > --- a/virtproxy.c
> > > +++ b/virtproxy.c
> > > @@ -13,6 +13,23 @@
> > >
> > >   #include "virtproxy.h"
> > >
> > > +#define DEBUG_VP
> > > +
> > > +#ifdef DEBUG_VP
> > > +#define TRACE(msg, ...) do { \
> > > +    fprintf(stderr, "%s:%s():L%d: " msg "\n", \
> > > +            __FILE__, __FUNCTION__, __LINE__, ## __VA_ARGS__); \
> > > +} while(0)
> > > +#else
> > > +#define TRACE(msg, ...) \
> > > +    do { } while (0)
> > > +#endif
> > > +
> > > +#define LOG(msg, ...) do { \
> > > +    fprintf(stderr, "%s:%s(): " msg "\n", \
> > > +            __FILE__, __FUNCTION__, ## __VA_ARGS__); \
> > > +} while(0)
> > > +
> >
> > I wonder if it wouldn't make sense to do this in a more generic way and
> > stick it in a header file. This type of debug code seems to show up
> > repeatedly all over the place.
>
> I wanted to suggest actually using QEMU tracing but given that this
> code compiles stand-alone, it may be more trouble to integrate than
> it's worth.
>
> For qemu and qemu-tools code we should be using tracing because you
> can build it into production without high overhead.  How often do
> these #defines get used, not often is my guess because no one wants to
> tweak the source and rebuild, especially not in production.

I'd planned on replacing the TRACE()'s with trace calls eventually. 
Maybe I missed it in the documentation, but do we have a way to enable 
them for qemu-tools or does we need to provide our own hooks and do it 
programmatically?

> Stefan