| 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 0x40000 /* arch specific */ |
| 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 | static void check_bytes(char *addr) |
| 35 | { |
| 36 | printf("First hex is %x\n", *((unsigned int *)addr)); |
| 37 | } |
| 38 | |
| 39 | static 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 | static 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 | } |