forked from Qortal/Brooklyn
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
93 lines
2.1 KiB
93 lines
2.1 KiB
// SPDX-License-Identifier: GPL-2.0 |
|
/* |
|
* hugepage-mmap: |
|
* |
|
* Example of using huge page memory in a user application using the mmap |
|
* system call. Before running this application, make sure that the |
|
* administrator has mounted the hugetlbfs filesystem (on some directory |
|
* like /mnt) using the command mount -t hugetlbfs nodev /mnt. In this |
|
* example, the app is requesting memory of size 256MB that is backed by |
|
* huge pages. |
|
* |
|
* For the ia64 architecture, the Linux kernel reserves Region number 4 for |
|
* huge pages. That means that if one requires a fixed address, a huge page |
|
* aligned address starting with 0x800000... will be required. If a fixed |
|
* address is not required, the kernel will select an address in the proper |
|
* range. |
|
* Other architectures, such as ppc64, i386 or x86_64 are not so constrained. |
|
*/ |
|
|
|
#include <stdlib.h> |
|
#include <stdio.h> |
|
#include <unistd.h> |
|
#include <sys/mman.h> |
|
#include <fcntl.h> |
|
|
|
#define FILE_NAME "huge/hugepagefile" |
|
#define LENGTH (256UL*1024*1024) |
|
#define PROTECTION (PROT_READ | PROT_WRITE) |
|
|
|
/* Only ia64 requires this */ |
|
#ifdef __ia64__ |
|
#define ADDR (void *)(0x8000000000000000UL) |
|
#define FLAGS (MAP_SHARED | MAP_FIXED) |
|
#else |
|
#define ADDR (void *)(0x0UL) |
|
#define FLAGS (MAP_SHARED) |
|
#endif |
|
|
|
static void check_bytes(char *addr) |
|
{ |
|
printf("First hex is %x\n", *((unsigned int *)addr)); |
|
} |
|
|
|
static void write_bytes(char *addr) |
|
{ |
|
unsigned long i; |
|
|
|
for (i = 0; i < LENGTH; i++) |
|
*(addr + i) = (char)i; |
|
} |
|
|
|
static int read_bytes(char *addr) |
|
{ |
|
unsigned long i; |
|
|
|
check_bytes(addr); |
|
for (i = 0; i < LENGTH; i++) |
|
if (*(addr + i) != (char)i) { |
|
printf("Mismatch at %lu\n", i); |
|
return 1; |
|
} |
|
return 0; |
|
} |
|
|
|
int main(void) |
|
{ |
|
void *addr; |
|
int fd, ret; |
|
|
|
fd = open(FILE_NAME, O_CREAT | O_RDWR, 0755); |
|
if (fd < 0) { |
|
perror("Open failed"); |
|
exit(1); |
|
} |
|
|
|
addr = mmap(ADDR, LENGTH, PROTECTION, FLAGS, fd, 0); |
|
if (addr == MAP_FAILED) { |
|
perror("mmap"); |
|
unlink(FILE_NAME); |
|
exit(1); |
|
} |
|
|
|
printf("Returned address is %p\n", addr); |
|
check_bytes(addr); |
|
write_bytes(addr); |
|
ret = read_bytes(addr); |
|
|
|
munmap(addr, LENGTH); |
|
close(fd); |
|
unlink(FILE_NAME); |
|
|
|
return ret; |
|
}
|
|
|