리눅스 커널 헤더 파일중 noderef, address_space attribute이 무엇인지요?

[bushi@rose net]$ cat -n ref.c
     1	#ifdef __CHECK__
     2	# define __noderef __attribute__((noderef))
     3	#else
     4	# define __noderef 
     5	#endif
     6	
     7	int main(int argc, char **argv)
     8	{
     9		int a = 3;
    10		int __noderef *pa_noderef;
    11		int *pa;
    12	
    13		pa_noderef = (int __noderef *)&a;
    14		pa = &a;
    15	
    16		*pa = 0;
    17		*pa_noderef = 0;
    18	
    19		return 0;
    20	}
[bushi@rose net]$ 
[bushi@rose net]$ sparse ref.c -D__CHECK__
ref.c:17:3: warning: dereference of noderef expression
[bushi@rose net]$

[bushi@rose net]$ cat -n space.c 
     1	#ifdef __CHECK__
     2	#define __pool1 __attribute__((address_space(1)))
     3	#define __pool2 __attribute__((address_space(2)))
     4	extern void __chk_pool1_ptr(const volatile void __pool1 *);
     5	extern void __chk_pool2_ptr(const volatile void __pool2 *);
     6	#else
     7	#define __pool1
     8	#define __pool2
     9	#define __chk_pool1_ptr(x) (void*)(0)
    10	#define __chk_pool2_ptr(x) (void*)(0)
    11	#endif
    12	
    13	int main(int argc, char **argv)
    14	{
    15		char __pool1 *c1;
    16		char __pool2 *c2;
    17	
    18		__chk_pool1_ptr(c1);
    19		__chk_pool2_ptr(c1);
    20	
    21		__chk_pool1_ptr(c2);
    22		__chk_pool2_ptr(c2);
    23		
    24		return 0;
    25	}
[bushi@rose net]$ 
[bushi@rose net]$ sparse space.c -D__CHECK__
space.c:19:18: warning: incorrect type in argument 1 (different address spaces)
space.c:19:18:    expected void const volatile <asn:2>*<noident>
space.c:19:18:    got char <asn:1>*c1
space.c:21:18: warning: incorrect type in argument 1 (different address spaces)
space.c:21:18:    expected void const volatile <asn:1>*<noident>
space.c:21:18:    got char <asn:2>*c2
[bushi@rose net]$