Re: Dynamic debug on by default?

From: Greg KH
Date: Wed Aug 14 2013 - 13:02:42 EST

On Wed, Aug 14, 2013 at 09:51:54AM -0700, Joe Perches wrote:
> 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

Yes, that's the problem, I'm trying to get rid of the CONFIG_USB_DEBUG
flag, and I'm almost there. There are some host controllers that still
use it for some things that I have not cleaned up fully yet.


greg k-h
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