2 * Copyright 2013-2015, Michael Ellerman, IBM Corp.
3 * Licensed under GPLv2.
6 #define _GNU_SOURCE /* For CPU_ZERO etc. */
16 #include <sys/types.h>
17 #include <sys/utsname.h>
22 static char auxv[4096];
24 int read_auxv(char *buf, ssize_t buf_size)
29 fd = open("/proc/self/auxv", O_RDONLY);
35 num = read(fd, buf, buf_size);
43 printf("overflowed auxv buffer\n");
54 void *find_auxv_entry(int type, char *auxv)
58 p = (ElfW(auxv_t) *)auxv;
60 while (p->a_type != AT_NULL) {
61 if (p->a_type == type)
70 void *get_auxv_entry(int type)
74 if (read_auxv(auxv, sizeof(auxv)))
77 p = find_auxv_entry(type, auxv);
79 return (void *)p->a_un.a_val;
84 int pick_online_cpu(void)
91 if (sched_getaffinity(0, sizeof(mask), &mask)) {
92 perror("sched_getaffinity");
96 /* We prefer a primary thread, but skip 0 */
97 for (cpu = 8; cpu < CPU_SETSIZE; cpu += 8)
98 if (CPU_ISSET(cpu, &mask))
101 /* Search for anything, but in reverse */
102 for (cpu = CPU_SETSIZE - 1; cpu >= 0; cpu--)
103 if (CPU_ISSET(cpu, &mask))
106 printf("No cpus in affinity mask?!\n");
110 bool is_ppc64le(void)
122 return strcmp(uts.machine, "ppc64le") == 0;