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authorRussell King <rmk+kernel@arm.linux.org.uk>2009-09-24 16:22:33 -0400
committerRussell King <rmk+kernel@arm.linux.org.uk>2009-09-24 16:22:33 -0400
commitbaea7b946f00a291b166ccae7fcfed6c01530cc6 (patch)
tree4aa275fbdbec9c7b9b4629e8bee2bbecd3c6a6af /Documentation/vm/map_hugetlb.c
parentae19ffbadc1b2100285a5b5b3d0a4e0a11390904 (diff)
parent94e0fb086fc5663c38bbc0fe86d698be8314f82f (diff)
Merge branch 'origin' into for-linus
Conflicts: MAINTAINERS
Diffstat (limited to 'Documentation/vm/map_hugetlb.c')
-rw-r--r--Documentation/vm/map_hugetlb.c77
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
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+++ 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
34void check_bytes(char *addr)
35{
36 printf("First hex is %x\n", *((unsigned int *)addr));
37}
38
39void write_bytes(char *addr)
40{
41 unsigned long i;
42
43 for (i = 0; i < LENGTH; i++)
44 *(addr + i) = (char)i;
45}
46
47void 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
59int 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}