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Re: [Qemu-devel] Patch to add helpful tracing output for driver authors
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] Patch to add helpful tracing output for driver authors in NVMe emulation |
Date: |
Fri, 6 Oct 2017 08:50:31 -0500 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.3.0 |
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 <address@hidden>
> 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 <address@hidden>
> ---
> 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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- [Qemu-devel] Patch to add helpful tracing output for driver authors in NVMe emulation, Doug Gale, 2017/10/05
- Re: [Qemu-devel] Patch to add helpful tracing output for driver authors in NVMe emulation, Kevin Wolf, 2017/10/06
- Re: [Qemu-devel] Patch to add helpful tracing output for driver authors in NVMe emulation,
Eric Blake <=
- Re: [Qemu-devel] Patch to add helpful tracing output for driver authors in NVMe emulation, Daniel P. Berrange, 2017/10/06
- Re: [Qemu-devel] Patch to add helpful tracing output for driver authors in NVMe emulation, Doug Gale, 2017/10/06
- Re: [Qemu-devel] Patch to add helpful tracing output for driver authors in NVMe emulation, Daniel P. Berrange, 2017/10/06
- Re: [Qemu-devel] Patch to add helpful tracing output for driver authors in NVMe emulation, Doug Gale, 2017/10/07
- Re: [Qemu-devel] Patch to add helpful tracing output for driver authors in NVMe emulation, Eric Blake, 2017/10/09
- Re: [Qemu-devel] Patch to add helpful tracing output for driver authors in NVMe emulation, Doug Gale, 2017/10/09
- Re: [Qemu-devel] Patch to add helpful tracing output for driver authors in NVMe emulation, Markus Armbruster, 2017/10/10
- Re: [Qemu-devel] Patch to add helpful tracing output for driver authors in NVMe emulation, Kevin Wolf, 2017/10/10
- Re: [Qemu-devel] Patch to add helpful tracing output for driver authors in NVMe emulation, Doug Gale, 2017/10/11
- Re: [Qemu-devel] Patch to add helpful tracing output for driver authors in NVMe emulation, Peter Maydell, 2017/10/11