x86: Document x86_init.paging.pagetable_init()

Signed-off-by: Attilio Rao <attilio.rao@citrix.com>
Acked-by: <konrad.wilk@oracle.com>
Cc: <Ian.Campbell@citrix.com>
Cc: <Stefano.Stabellini@eu.citrix.com>
Cc: <xen-devel@lists.xensource.com>
Link: http://lkml.kernel.org/r/1345580561-8506-6-git-send-email-attilio.rao@citrix.comSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/include/asm/x86_init.h

@@ -81,7 +81,10 @@ struct x86_init_mapping {
 
 /**
  * struct x86_init_paging - platform specific paging functions
- * @pagetable_init:		platform specific paging initialization call
+ * @pagetable_init:	platform specific paging initialization call to setup
+ *			the kernel pagetables and prepare accessors functions.
+ *			Callback must call paging_init(). Called once after the
+ *			direct mapping for phys memory is available.
  */
 struct x86_init_paging {
 	void (*pagetable_init)(void);