On 10/05/2017 06:18 PM, Doug Gale wrote: > I added the tracing output in this patch to assist me in implementing > an NVMe driver. It helped tremendously. > >>From 1d19086cdef8d492929852d582cb41dcc5026f71 Mon Sep 17 00:00:00 2001 > From: Doug Gale <doug...@gmail.com> > Date: Thu, 5 Oct 2017 19:02:03 -0400 > Subject: [PATCH] Add tracing output to NVMe emulation to help driver authors. > > It is off by default, enable it by uncommenting #define DEBUG_NVME > or through CFLAGS > > Signed-off-by: Doug Gale <doug...@gmail.com> > --- > hw/block/nvme.c | 191 > +++++++++++++++++++++++++++++++++++++++++++++++++++----- > 1 file changed, 177 insertions(+), 14 deletions(-) > > diff --git a/hw/block/nvme.c b/hw/block/nvme.c > index 9aa32692a3..74220c0171 100644 > --- a/hw/block/nvme.c > +++ b/hw/block/nvme.c > @@ -36,6 +36,14 @@ > > #include "nvme.h" > > +//#define DEBUG_NVME > + > +#ifdef DEBUG_NVME > +#define DPRINTF(fmt, ...) fprintf(stderr, "nvme: " fmt "\n", ## __VA_ARGS__) > +#else > +#define DPRINTF(fmt, ...) ((void)0) > +#endif
As Kevin said, using trace-events is nicer than fprintf(). But if you
absolutely insist on fprintf(), then do NOT do it like this, because
this leads to bit-rot. Instead, do it in a form that lets -Wformat
checking work even when tracing is disabled:
#ifdef DEBUG_NVME
# define DEBUG_NVME_PRINT 1
#else
# define DEBUG_NVME_PRINT 0
#endif
#define DPRINTF(fmt, ...) \
do { \
if (DEBUG_NVME_PRINT) { \
fprintf(stderr, "nvme: " fmt "\n", ## __VA_ARGS__); \
} \
while (0)
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
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