From: Joe Perches <joe@perches.com>
To: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: Xenia Ragiadakou <burzalodowa@gmail.com>,
Jason Baron <jbaron@akamai.com>,
Greg KH <gregkh@linuxfoundation.org>,
linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: Dynamic debug on by default?
Date: Wed, 14 Aug 2013 09:51:54 -0700 [thread overview]
Message-ID: <1376499114.1949.81.camel@joe-AO722> (raw)
In-Reply-To: <20130814164022.GA22934@xanatos>
On Wed, 2013-08-14 at 09:40 -0700, Sarah Sharp wrote:
> Hi Xenia,
>
> I'm a bit confused. I thought that debugging messages would be turned
> off by default for a module if CONFIG_DYNAMIC_DEBUG was turned on. When
> I tested your patch to remove the CONFIG_USB_XHCI_HCD_DEBUGGING and just
> use dev_dbg, the messages from the xHCI driver appeared in dmesg by
> default.
>
> That generates a lot of log spew. We can have distros add a boot
> parameter option to turn off debug messages, but that boot parameter is
> limited to 1023 characters. I'm concerned that if more drivers add
> dynamic debugging, the distros will eventually run out of space in the
> dynamic debugging boot parameter. I know Greg was ripping out debugging
> config options in other USB drivers, so this is a bit concerning.
>
> Jason, is there a way within the xHCI driver to say that dynamic
> debugging should be off by default? I've looked through the
> documentation, and I can't find anything like that documented.
#undefine DEBUG
> I've attached my .config file, in case I have something misconfigured.
Because of:
drivers/usb/host/Makefile:ccflags-$(CONFIG_USB_DEBUG) := -DDEBUG
you probably want to turn this off
CONFIG_USB_DEBUG=y
when dynamic_debug is on.
CONFIG_DYNAMIC_DEBUG=y
This will cause all pr_debug/dev_dbg statements to be
emitted without specific enabling via the dynamic_debug
control file.
(from include/linux/dynamic_debug.h)
#if defined DEBUG
#define _DPRINTK_FLAGS_DEFAULT _DPRINTK_FLAGS_PRINT
#else
#define _DPRINTK_FLAGS_DEFAULT 0
#endif
next prev parent reply other threads:[~2013-08-14 16:51 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-14 16:40 Sarah Sharp
2013-08-14 16:51 ` Joe Perches [this message]
2013-08-14 17:04 ` Greg KH
2013-08-14 17:20 ` Sarah Sharp
2013-08-14 18:02 ` Greg KH
2013-08-14 18:21 ` Jason Baron
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