1. 根目录:
2. arch
3. x86
4. mm
5. physaddr.h

#include <asm/processor.h>

static inline int phys_addr_valid(resource_size_t addr)
{
#ifdef CONFIG_PHYS_ADDR_T_64BIT
	return !(addr >> boot_cpu_data.x86_phys_bits);
#else
	return 1;
#endif
}