mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-12 06:46:51 +07:00
94bf5ceac0
Add an example of how to use the MAP_HUGETLB flag to the vm documentation directory and a reference to the example in hugetlbpage.txt. Signed-off-by: Eric B Munson <ebmunson@us.ibm.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Adam Litke <agl@us.ibm.com> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
78 lines
1.6 KiB
C
78 lines
1.6 KiB
C
/*
|
|
* Example of using hugepage memory in a user application using the mmap
|
|
* system call with MAP_HUGETLB flag. Before running this program make
|
|
* sure the administrator has allocated enough default sized huge pages
|
|
* to cover the 256 MB allocation.
|
|
*
|
|
* For ia64 architecture, Linux kernel reserves Region number 4 for hugepages.
|
|
* That means the addresses starting with 0x800000... will need to be
|
|
* specified. Specifying a fixed address is not required on ppc64, i386
|
|
* or x86_64.
|
|
*/
|
|
#include <stdlib.h>
|
|
#include <stdio.h>
|
|
#include <unistd.h>
|
|
#include <sys/mman.h>
|
|
#include <fcntl.h>
|
|
|
|
#define LENGTH (256UL*1024*1024)
|
|
#define PROTECTION (PROT_READ | PROT_WRITE)
|
|
|
|
#ifndef MAP_HUGETLB
|
|
#define MAP_HUGETLB 0x40
|
|
#endif
|
|
|
|
/* Only ia64 requires this */
|
|
#ifdef __ia64__
|
|
#define ADDR (void *)(0x8000000000000000UL)
|
|
#define FLAGS (MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB | MAP_FIXED)
|
|
#else
|
|
#define ADDR (void *)(0x0UL)
|
|
#define FLAGS (MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB)
|
|
#endif
|
|
|
|
void check_bytes(char *addr)
|
|
{
|
|
printf("First hex is %x\n", *((unsigned int *)addr));
|
|
}
|
|
|
|
void write_bytes(char *addr)
|
|
{
|
|
unsigned long i;
|
|
|
|
for (i = 0; i < LENGTH; i++)
|
|
*(addr + i) = (char)i;
|
|
}
|
|
|
|
void 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);
|
|
break;
|
|
}
|
|
}
|
|
|
|
int main(void)
|
|
{
|
|
void *addr;
|
|
|
|
addr = mmap(ADDR, LENGTH, PROTECTION, FLAGS, 0, 0);
|
|
if (addr == MAP_FAILED) {
|
|
perror("mmap");
|
|
exit(1);
|
|
}
|
|
|
|
printf("Returned address is %p\n", addr);
|
|
check_bytes(addr);
|
|
write_bytes(addr);
|
|
read_bytes(addr);
|
|
|
|
munmap(addr, LENGTH);
|
|
|
|
return 0;
|
|
}
|