On (23/04/03 23:39), Jaewon Kim wrote: [..] > > Okay, then we can't use %09pK. I've just wondered because %9pK works. This is not per printk / kernel, Wformat warnings come from the compiler. Per C11 (7.21.6 6): 0 For d, i, o, u, x, X, a, A, e, E, f, F, g, and G conversions, leading zeros (following any indication of sign or base) are used to pad to the field width rather than performing space padding ... For other conversions, the behavior is undefined. So using 0 for p should trigger an undefined behavior as far as the standard C concerned. Unless I'm missing something.