Re: [Qemu-devel] [RFC PATCH 1/3] virtio-bus : Introduce VirtioBus.

[Andreas Färber]

Am 21.11.2012 15:05, schrieb KONRAD Frédéric:
> On 21/11/2012 14:04, Andreas Färber wrote:
>> Am 16.11.2012 16:35, schrieb address@hidden:
>>> +#define DEBUG_VIRTIO_BUS
>>> +
>>> +#ifdef DEBUG_VIRTIO_BUS
>>> +
>>> +#define DPRINTF(fmt, ...) \
>>> +do { printf("virtio_bus: " fmt , ## __VA_ARGS__); } while (0)
>>> +#else
>>> +#define DPRINTF(fmt, ...) do {} while (0)
>>> +#endif
>> We recently had a discussion about bitrotting DPRINTF() statements where
>> I suggested to use if (0) instead of a no-op macro like this that
>> doesn't reference fmt and the varargs.
> I don't understand what you suggested, can you point me to an example ?

I don't have a link at hand, maybe Evgeny does. It was along the lines of:

#define DEBUG_VIRTIO_BUS 0

#define DPRINTF(fmt, ...) if (DEBUG_VIRTIO_BUS) { \
        printf("virtio_bus: " fmt , ## __VA_ARGS__); \
    }

The officially preferred alternative is to use tracepoints. ;)

Cheers,
Andreas

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