1. 根目录:
2. include
3. asm-generic
4. bitsperlong.h

#ifndef __ASM_GENERIC_BITS_PER_LONG
#define __ASM_GENERIC_BITS_PER_LONG

#include <uapi/asm-generic/bitsperlong.h>


#ifdef CONFIG_64BIT
#define BITS_PER_LONG 64
#else
#define BITS_PER_LONG 32
#endif /* CONFIG_64BIT */

/*
 * FIXME: The check currently breaks x86-64 build, so it's
 * temporarily disabled. Please fix x86-64 and reenable
 */
#if 0 && BITS_PER_LONG != __BITS_PER_LONG
#error Inconsistent word size. Check asm/bitsperlong.h
#endif

#ifndef BITS_PER_LONG_LONG
#define BITS_PER_LONG_LONG 64
#endif

#endif /* __ASM_GENERIC_BITS_PER_LONG */