April 19, 2012
6:54 a.m.
Hi, In Linux code we add a guard macro to avoid multiple declarations of identifiers. But I see some macros defined with trailing underscores. e.g. In arch/x86/include/asm/ Normally it is defined like, #ifndef _ASM_X86_ALTERNATIVE_H #define _ASM_X86_ALTERNATIVE_H But in some files I see trailing underscore after H , e.g. arch/x86/include/asm/intel_scu_ipc.h #ifndef _ASM_X86_INTEL_SCU_IPC_H_ #define _ASM_X86_INTEL_SCU_IPC_H_ There are others files also arch/x86/include/asm/irqflags.h http://lxr.linux.no/#linux+v3.3.2/arch/x86/include/asm/probe_roms.h DOES THIS TRAILING UNDERSCORE HAS SPECIAL MEANING ??? Thanks -- Pritam Bankar