2 * Copyright 2013-2015, Michael Ellerman, IBM Corp.
3 * Licensed under GPLv2.
6 #define _GNU_SOURCE /* For CPU_ZERO etc. */
15 #include <sys/types.h>
20 static char auxv[4096];
22 void *get_auxv_entry(int type)
29 fd = open("/proc/self/auxv", O_RDONLY);
37 num = read(fd, auxv, sizeof(auxv));
43 if (num > sizeof(auxv)) {
44 printf("Overflowed auxv buffer\n");
48 p = (ElfW(auxv_t) *)auxv;
50 while (p->a_type != AT_NULL) {
51 if (p->a_type == type) {
52 result = (void *)p->a_un.a_val;
63 int pick_online_cpu(void)
70 if (sched_getaffinity(0, sizeof(mask), &mask)) {
71 perror("sched_getaffinity");
75 /* We prefer a primary thread, but skip 0 */
76 for (cpu = 8; cpu < CPU_SETSIZE; cpu += 8)
77 if (CPU_ISSET(cpu, &mask))
80 /* Search for anything, but in reverse */
81 for (cpu = CPU_SETSIZE - 1; cpu >= 0; cpu--)
82 if (CPU_ISSET(cpu, &mask))
85 printf("No cpus in affinity mask?!\n");