Messages in this thread Patch in this message | | | From | Orson Zhai <> | Date | Sat, 21 Mar 2020 12:25:19 +0800 | Subject | Re: [RFC PATCH] dynamic_debug: Add config option of DYNAMIC_DEBUG_CORE |
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Hi Jason,
On Thu, Mar 19, 2020 at 5:18 AM Jason Baron <jbaron@akamai.com> wrote: > > > > On 3/18/20 3:03 PM, Orson Zhai wrote: > > There is the requirement from new Android that kernel image (GKI) and > > kernel modules are supposed to be built at differnet places. Some people > > want to enable dynamic debug for kernel modules only but not for kernel > > image itself with the consideration of binary size increased or more > > memory being used. > > > > By this patch, dynamic debug is divided into core part (the defination of > > functions) and macro replacement part. We can only have the core part to > > be built-in and do not have to activate the debug output from kenrel image. > > > > Signed-off-by: Orson Zhai <orson.unisoc@gmail.com> > > Hi Orson, > > I think this is a nice feature. Is the idea then that driver can do > something like: > > #if defined(CONFIG_DRIVER_FOO_DEBUG) > #define driver_foo_debug(fmt, ...) \ > dynamic_pr_debug(fmt, ##__VA_ARGS__) > #else > no_printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__) > #enif
I am thinking this again. Why don't we add a local macro ( I mean not like the global macro from Kconfig ) just like the DEBUG macro? Say DDEBUG or DYN_DEBUG.
We can add this to printk.h to let module owners decide when & which module should be dynamic debugged? #ifdef CONFIG_DYNAMIC_DUBUG || DDEUG .....
Module owner can add this to his module's Makefile, for example: .... ccflags-$(CONFIG_UFS_DEBUG) += -DDDEBUG .... This will enable macro replacement for even a single c file.
How do you think about it?
Best, -Orson
> > And then the Kconfig: > > config DYNAMIC_DRIVER_FOO_DEBUG > bool "Enable dynamic driver foo printk() support" > select DYNAMIC_DEBUG_CORE > > > Or did you have something else in mind? Do you have an example > code for the drivers that you mention? > > Thanks, > > -Jason > > > > --- > > include/linux/dynamic_debug.h | 2 +- > > lib/Kconfig.debug | 18 ++++++++++++++++-- > > lib/Makefile | 2 +- > > 3 files changed, 18 insertions(+), 4 deletions(-) > > > > diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h > > index 4cf02ec..abcd5fd 100644 > > --- a/include/linux/dynamic_debug.h > > +++ b/include/linux/dynamic_debug.h > > @@ -48,7 +48,7 @@ struct _ddebug { > > > > > > > > -#if defined(CONFIG_DYNAMIC_DEBUG) > > +#if defined(CONFIG_DYNAMIC_DEBUG_CORE) > > int ddebug_add_module(struct _ddebug *tab, unsigned int n, > > const char *modname); > > extern int ddebug_remove_module(const char *mod_name); > > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > > index 69def4a..78a7256 100644 > > --- a/lib/Kconfig.debug > > +++ b/lib/Kconfig.debug > > @@ -97,8 +97,7 @@ config BOOT_PRINTK_DELAY > > config DYNAMIC_DEBUG > > bool "Enable dynamic printk() support" > > default n > > - depends on PRINTK > > - depends on DEBUG_FS > > + select DYNAMIC_DEBUG_CORE > > help > > > > Compiles debug level messages into the kernel, which would not > > @@ -164,6 +163,21 @@ config DYNAMIC_DEBUG > > See Documentation/admin-guide/dynamic-debug-howto.rst for additional > > information. > > > > +config DYNAMIC_DEBUG_CORE > > + bool "Enable core functions of dynamic debug support" > > + depends on PRINTK > > + depends on DEBUG_FS > > + help > > + Enable this option to build ddebug_* and __dynamic_* routines > > + into kernel. If you want enable whole dynamic debug features, > > + select CONFIG_DYNAMIC_DEBUG directly and this option will be > > + automatically selected. > > + > > + This option is selected when you want to enable dynamic debug > > + for kernel modules only but not for the kernel base. Especailly > > + in the case that kernel modules are built out of the place where > > + kernel base is built. > > + > > config SYMBOLIC_ERRNAME > > bool "Support symbolic error names in printf" > > default y if PRINTK > > diff --git a/lib/Makefile b/lib/Makefile > > index 611872c..2096d83 100644 > > --- a/lib/Makefile > > +++ b/lib/Makefile > > @@ -183,7 +183,7 @@ lib-$(CONFIG_GENERIC_BUG) += bug.o > > > > obj-$(CONFIG_HAVE_ARCH_TRACEHOOK) += syscall.o > > > > -obj-$(CONFIG_DYNAMIC_DEBUG) += dynamic_debug.o > > +obj-$(CONFIG_DYNAMIC_DEBUG_CORE) += dynamic_debug.o > > obj-$(CONFIG_SYMBOLIC_ERRNAME) += errname.o > > > > obj-$(CONFIG_NLATTR) += nlattr.o > >
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