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Date: Wed, 21 Nov 2012 15:13:01 +0100
From: =?ISO-8859-15?Q?Andreas_F=E4rber?= <afaerber@suse.de>
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Subject: Re: [Qemu-devel] [RFC PATCH 1/3] virtio-bus : Introduce VirtioBus.
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To: =?ISO-8859-15?Q?KONRAD_Fr=E9d=E9ric?= <fred.konrad@greensocs.com>
Cc: Peter Maydell <peter.maydell@linaro.org>, Stefan Hajnoczi <stefanha@redhat.com>, Evgeny Voevodin <e.voevodin@samsung.com>, mark.burton@greensocs.com, qemu-devel@nongnu.org, Anthony Liguori <anthony@codemonkey.ws>, Cornelia Huck <cornelia.huck@de.ibm.com>

Am 21.11.2012 15:05, schrieb KONRAD Fr=E9d=E9ric:
> On 21/11/2012 14:04, Andreas F=E4rber wrote:
>> Am 16.11.2012 16:35, schrieb fred.konrad@greensocs.com:
>>> +#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 whe=
re
>> 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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