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author | Russell King <rmk+kernel@arm.linux.org.uk> | 2009-09-24 16:22:33 -0400 |
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committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2009-09-24 16:22:33 -0400 |
commit | baea7b946f00a291b166ccae7fcfed6c01530cc6 (patch) | |
tree | 4aa275fbdbec9c7b9b4629e8bee2bbecd3c6a6af /Documentation/vm/map_hugetlb.c | |
parent | ae19ffbadc1b2100285a5b5b3d0a4e0a11390904 (diff) | |
parent | 94e0fb086fc5663c38bbc0fe86d698be8314f82f (diff) |
Merge branch 'origin' into for-linus
Conflicts:
MAINTAINERS
Diffstat (limited to 'Documentation/vm/map_hugetlb.c')
-rw-r--r-- | Documentation/vm/map_hugetlb.c | 77 |
1 files changed, 77 insertions, 0 deletions
diff --git a/Documentation/vm/map_hugetlb.c b/Documentation/vm/map_hugetlb.c new file mode 100644 index 000000000000..e2bdae37f499 --- /dev/null +++ b/Documentation/vm/map_hugetlb.c | |||
@@ -0,0 +1,77 @@ | |||
1 | /* | ||
2 | * Example of using hugepage memory in a user application using the mmap | ||
3 | * system call with MAP_HUGETLB flag. Before running this program make | ||
4 | * sure the administrator has allocated enough default sized huge pages | ||
5 | * to cover the 256 MB allocation. | ||
6 | * | ||
7 | * For ia64 architecture, Linux kernel reserves Region number 4 for hugepages. | ||
8 | * That means the addresses starting with 0x800000... will need to be | ||
9 | * specified. Specifying a fixed address is not required on ppc64, i386 | ||
10 | * or x86_64. | ||
11 | */ | ||
12 | #include <stdlib.h> | ||
13 | #include <stdio.h> | ||
14 | #include <unistd.h> | ||
15 | #include <sys/mman.h> | ||
16 | #include <fcntl.h> | ||
17 | |||
18 | #define LENGTH (256UL*1024*1024) | ||
19 | #define PROTECTION (PROT_READ | PROT_WRITE) | ||
20 | |||
21 | #ifndef MAP_HUGETLB | ||
22 | #define MAP_HUGETLB 0x40 | ||
23 | #endif | ||
24 | |||
25 | /* Only ia64 requires this */ | ||
26 | #ifdef __ia64__ | ||
27 | #define ADDR (void *)(0x8000000000000000UL) | ||
28 | #define FLAGS (MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB | MAP_FIXED) | ||
29 | #else | ||
30 | #define ADDR (void *)(0x0UL) | ||
31 | #define FLAGS (MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB) | ||
32 | #endif | ||
33 | |||
34 | void check_bytes(char *addr) | ||
35 | { | ||
36 | printf("First hex is %x\n", *((unsigned int *)addr)); | ||
37 | } | ||
38 | |||
39 | void write_bytes(char *addr) | ||
40 | { | ||
41 | unsigned long i; | ||
42 | |||
43 | for (i = 0; i < LENGTH; i++) | ||
44 | *(addr + i) = (char)i; | ||
45 | } | ||
46 | |||
47 | void read_bytes(char *addr) | ||
48 | { | ||
49 | unsigned long i; | ||
50 | |||
51 | check_bytes(addr); | ||
52 | for (i = 0; i < LENGTH; i++) | ||
53 | if (*(addr + i) != (char)i) { | ||
54 | printf("Mismatch at %lu\n", i); | ||
55 | break; | ||
56 | } | ||
57 | } | ||
58 | |||
59 | int main(void) | ||
60 | { | ||
61 | void *addr; | ||
62 | |||
63 | addr = mmap(ADDR, LENGTH, PROTECTION, FLAGS, 0, 0); | ||
64 | if (addr == MAP_FAILED) { | ||
65 | perror("mmap"); | ||
66 | exit(1); | ||
67 | } | ||
68 | |||
69 | printf("Returned address is %p\n", addr); | ||
70 | check_bytes(addr); | ||
71 | write_bytes(addr); | ||
72 | read_bytes(addr); | ||
73 | |||
74 | munmap(addr, LENGTH); | ||
75 | |||
76 | return 0; | ||
77 | } | ||