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Implement machdep.cpu.core_count
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src/kernel/emulation/linux/misc/sysctl_machdep.c
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src/kernel/emulation/linux/misc/sysctl_machdep.c
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#include "simple.h"
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#include <sys/errno.h>
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#include <alloca.h>
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#include "../fcntl/open.h"
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#include "../readline.h"
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#include "../unistd/close.h"
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extern char *strncpy(char *dest, const char *src, __SIZE_TYPE__ n);
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extern int strncmp(const char* str1, const char* str2, __SIZE_TYPE__ n);;
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enum {
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_MACHDEP_CPU = 1000,
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_CPU_STEPPING,
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_CPU_BRAND_STRING,
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_CPU_FEATURES,
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_CPU_CORE_COUNT,
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};
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static sysctl_handler(handle_vendor);
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static sysctl_handler(handle_stepping);
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static sysctl_handler(handle_brand_string);
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static sysctl_handler(handle_features);
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static sysctl_handler(handle_core_count);
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const struct known_sysctl sysctls_machdep_cpu[] = {
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{ .oid = _CPU_MAX_BASIC, .type = CTLTYPE_INT, .exttype = "I", .name = "max_basic", .handler = handle_max_basic },
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{ .oid = _CPU_STEPPING, .type = CTLTYPE_INT, .exttype = "I", .name = "stepping", .handler = handle_stepping },
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{ .oid = _CPU_BRAND_STRING, .type = CTLTYPE_STRING, .exttype = "S", .name = "vendor", .handler = handle_brand_string },
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{ .oid = _CPU_FEATURES, .type = CTLTYPE_STRING, .exttype = "S", .name = "features", .handler = handle_features },
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{ .oid = _CPU_CORE_COUNT, .type = CTLTYPE_INT, .exttype = "I", .name = "core_count", .handler = handle_core_count },
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{ .oid = -1 }
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};
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···
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return 0;
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}
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// TODO: i doubt core count is ever going to change.
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// this is something that could be cached if we had some way of doing something only once in libsystem_kernel (i.e. a simple version of dispatch_once).
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sysctl_handler(handle_core_count) {
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// it's easier to use /proc/cpuinfo for this.
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// using cpuid directly is more difficult because AMD processors don't use the same method as Intel processors.
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int infofd = sys_open_nocancel("/proc/cpuinfo", BSD_O_RDONLY, 0);
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struct rdline_buffer rbuf;
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const char* line;
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// a reasonable default
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size_t core_count = 1;
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if (infofd < 0)
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goto out;
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_readline_init(&rbuf);
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while ((line = _readline(infofd, &rbuf)) != NULL) {
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if (strncmp(line, "cpu cores", 9) != 0) {
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continue;
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}
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// great, we've got "cpu cores"
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// now find the actual number
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while (*line != ':' && *line != '\0')
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++line;
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// shouldn't happen, but just in case
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if (*line == '\0')
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continue;
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++line; // skip the colon
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if (*line == '\0')
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continue;
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++line; // skip the space
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if (*line == '\0')
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continue;
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core_count = __simple_atoi(line, NULL);
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break;
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}
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out:
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if (infofd >= 0)
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close_internal(infofd);
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if (old != NULL && oldlen && *oldlen >= sizeof(uint32_t))
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*(uint32_t*)old = core_count;
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if (oldlen)
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*oldlen = sizeof(uint32_t);
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return 0;
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};