Messages in this thread | | | Date | Wed, 21 May 2008 13:35:19 -0700 | From | Randy Dunlap <> | Subject | Re: [patch 1/3] dynamic_printk: core |
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On Tue, 29 Apr 2008 14:41:43 -0400 Jason Baron wrote:
> > Add the ability to dynamically enable/disable pr_debug()/dev_dbg() in the > kernel. Yes, these calls could be converted to printk(KERN_DEBUG), but there > are enough to cause overhead. Additionally, the logs become difficult to read. > Here, one can turn these messages on/off per module via: > > echo "add module_name" > <debugfs>/dynamic_printk/modules > echo "remove module_name" > <debugfs>/dynamic_printk/modules > > There is also a special 'all' value that turns on all the debugging messages. > ---
> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > index 623ef24..63e5229 100644 > --- a/lib/Kconfig.debug > +++ b/lib/Kconfig.debug > @@ -632,6 +632,46 @@ config FIREWIRE_OHCI_REMOTE_DMA > > If unsure, say N. > > +config DYNAMIC_PRINTK > + bool "Enable dynamic printk() call support" > + default n > + depends on PRINTK
and depends on DEBUG_FS ??
We shouldn't advertise this option unless the kernel can actually enable those pr_debug/dev_dbg calls...
> + help > + > + Allows pr_debug() and dev_dbg() calls to be dynamically enabled based > + upon their source module. Traditionally, these calls are only > + enabled if one set #define DEBUG and recompiled the kernel. This > + option obviates time consuming re-compiles. > + > + The impact of this compile option is a larger kerenl text size ~1%. > + However, if CONFIG_IMMEDIATE is set, the run-time impact is > + negligible. Without CONFIG_IMMEDIATE set, a global variable is > + referenced for each pr_debug() and dev_dbg() calls. > + > + Usage: > + > + The printing of pr_debug() and dev_dbg() is controlled by the > + debugfs file, dynamic_printk/modules. This file contains a list of > + the active modules. To add and remove modules: > + > + echo "add <module_name>" > dynamic_printk/modules > + echo "remove <module_name>" > dynamic_printk/modules > + > + For example: > + > + echo "add kobject" > dynamic_printk/modules > + /sbin/modprobe <module> > + > + This will cause kobject debug messages to spew out. Also, a special > + "all" value will print all pr_debug() and dev_dbg() calls. I.e.: > + > + echo "add all" > dynamic_printk/modules > + echo "remove all" > dynamic_printk/modules > + > + Finally, passing "dynamic_printk" at the command line enables all > + pr_debug() and dev_dbg() call to come out (same as "all"). This mode > + can be disabled via a "remove all". > + > source "samples/Kconfig" > > source "lib/Kconfig.kgdb"
--- ~Randy
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