[RFC] init: introduce boot param alias

[RFC] init: introduce boot param alias

[Cyrill Gorcunov]

By introducing the macroses __setup_alias and early_param_alias
we are allowed to use boot param aliases.

Here is an example:

static int __init parse_func(char *arg)
{
	/* set some flag or do something */
	return 0;
}
early_param("param1", parse_func);
early_param_alias("param1-alias", parse_func);

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
---

I found it usefull while was looking for APIC code merging.
Please review! Any comments are _quite_welcome_!!!

I use __LINE__ macro to define salt for names. Not sure
if this is really that good way to produce unique names.
But anyway i think it's better then define different functions
with same functionallity.

I'm on really slow GPRS connection now and can't reply fast so
forgive me for that :)

Index: linux-2.6.git/include/linux/init.h
===================================================================
--- linux-2.6.git.orig/include/linux/init.h	2008-08-03 17:32:25.000000000 +0400
+++ linux-2.6.git/include/linux/init.h	2008-08-03 18:02:48.000000000 +0400
@@ -247,6 +247,25 @@ struct obs_kernel_param {
 #define early_param(str, fn)					\
 	__setup_param(str, fn, fn, 1)
 
+/*
+ * Sometimes we need to define boot parameter alias
+ * ie different boot options with the same functionality
+ * so we could use one parsing function for all of them
+ * NOTE: these macroses _MUST_ be placed on different lines
+ */
+#define __setup_param_alias(str, unique_id, salt, fn, early)		\
+	static char __setup_str_##unique_id##salt[] __initdata __aligned(1) = str; \
+	static struct obs_kernel_param __setup_##unique_id##salt	\
+		__used __section(.init.setup)				\
+		__attribute__((aligned((sizeof(long)))))		\
+		= { __setup_str_##unique_id##salt, fn, early }
+
+#define __setup_alias(str, fn)				\
+	__setup_param_alias(str, fn, __LINE__, fn, 0)
+
+#define early_param_alias(str, fn)			\
+	__setup_param_alias(str, fn, __LINE__, fn, 1)
+
 /* Relies on boot_command_line being set */
 void __init parse_early_param(void);
 #endif /* __ASSEMBLY__ */