Re: [U-Boot] [WIP, PATCH] initcall: An outline of the idea

Hi Graeme,

On Fri, Mar 02, 2012 at 10:05:12PM +1100, Graeme Russ wrote:

diff --git a/doc/README.INIT_FUNC b/doc/README.INIT_FUNC new file mode 100644 index 0000000..b545390 --- /dev/null +++ b/doc/README.INIT_FUNC @@ -0,0 +1,31 @@ +The INIT_FUNC macro allows initialisation functions (i.e. functions which are +executed before the main loop) to be easily added to the init sequence

+The format of the INIT_FUNC macro is:

+INIT_FUNC({function_name}, {init_class}, {prerequisite init_class(es)})

+{function_name} is the name of the init function to call. This function must +have the following prototype:

+int foo(void);

+Each init function must return 0 to indicate success - any other return value +indicates failure and the init sequence will stop

+{init_class} is a simple test string to describe the basic purpose of the init +function. Multiple init functions may share the same init_class string

+{prerequisite init_class(es)} is a list of init_class strings (see above) which +defines what init functions are executed before and after the given init +function. Each prerequisite init_class is seperated by a space and preceeded by +either:

• • • At least one function of this init class must exist (i.e. there must be at

• least one INIT_FUNC entry with {init_class} set to the init class named
  

• after the '*' - All init functions with an init class matching the class
  

• named after the '*' will be executed before this function
  

• • • All init functions with an init class matching the class named after the

• '+' will be executed before this function, but there does not need to be
  

• any functions with the named init class in the init sequence
  

• • • This function will be called before any other functions with the init

• class named after the '-'
  

What happens if there's a set of dependencies that cannot be resolved? From reading the above, it seems I can do something like this:

INIT_FUNC(ifunc1, class1, *class2); INIT_FUNC(ifunc2, class2, *class1);

It would also seem that if you want to change the prerequisites for a given init_class, you need to find every instance of INIT_FUNC for that init_class and change it.

Perhaps there's a better way of solving this, but it maybe there should be a separate place which names the init classes and their prerequisites?

diff --git a/include/initcall.h b/include/initcall.h new file mode 100644 index 0000000..a81cf21 --- /dev/null +++ b/include/initcall.h @@ -0,0 +1,19 @@ +#ifndef __INIT_CALL_H__ +#define __INIT_CALL_H__ +#include <linux/compiler.h> +#define INIT_FUNC(fn, init_name, deps) \

• static const char __init_func_ ## fn[] __used \
• __attribute__((__section__(".initfuncs"))) = \
• "(" #fn ":" #init_name ";" #deps ")\n";

+#define SKIP_INIT(init_name) \

• static const char __skip_init_ ## req[] __used \
• __attribute__((__section__(".initfuncs"))) = \
• "{" #init_name "}\n";

+#define REPLACE_INIT(old_func, new_func) \

• static const char __replace_init_ ## old_func[] __used \
• __attribute__((__section__(".initfuncs"))) = \
• "[" #old_func "," #new_func "]\n";

+#endif /* !__INIT_CALL_H__ */

What are SKIP_INIT() and REPLACE_INIT() used for?

Perhaps the macro could be expanded to include a prototype for the function, so that gcc complains with a useful error message if there's a type mismatch.

Bye for now,