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For Apple silicon, use machdep.cpu.brand_string in preference to decoding hw.machine #246

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Merged
digantdesai merged 1 commit into from
Mar 21, 2025
Merged

For Apple silicon, use machdep.cpu.brand_string in preference to decoding hw.machine #246

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30 changes: 25 additions & 5 deletions src/arm/mach/init.c
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Original file line number Diff line number Diff line change
Expand Up @@ -101,25 +101,42 @@ static enum cpuinfo_uarch decode_uarch(uint32_t cpu_family, uint32_t core_index,
return cpuinfo_uarch_unknown;
}

static void decode_package_name(char* package_name) {
static int read_package_name_from_brand_string(char* package_name) {
size_t size;
if (sysctlbyname("machdep.cpu.brand_string", NULL, &size, NULL, 0) != 0) {
sysctlfail:
cpuinfo_log_warning("sysctlbyname(\"machdep.cpu.brand_string\") failed: %s", strerror(errno));
return false;
}

char* brand_string = alloca(size);
if (sysctlbyname("machdep.cpu.brand_string", brand_string, &size, NULL, 0) != 0)
goto sysctlfail;
cpuinfo_log_debug("machdep.cpu.brand_string: %s", brand_string);

strlcpy(package_name, brand_string, CPUINFO_PACKAGE_NAME_MAX);
return true;
}

static int decode_package_name_from_hw_machine(char* package_name) {
size_t size;
if (sysctlbyname("hw.machine", NULL, &size, NULL, 0) != 0) {
cpuinfo_log_warning("sysctlbyname(\"hw.machine\") failed: %s", strerror(errno));
return;
return false;
}

char* machine_name = alloca(size);
if (sysctlbyname("hw.machine", machine_name, &size, NULL, 0) != 0) {
cpuinfo_log_warning("sysctlbyname(\"hw.machine\") failed: %s", strerror(errno));
return;
return false;
}
cpuinfo_log_debug("hw.machine: %s", machine_name);

char name[10];
uint32_t major = 0, minor = 0;
if (sscanf(machine_name, "%9[^,0123456789]%" SCNu32 ",%" SCNu32, name, &major, &minor) != 3) {
cpuinfo_log_warning("parsing \"hw.machine\" failed: %s", strerror(errno));
return;
return false;
}

uint32_t chip_model = 0;
Expand Down Expand Up @@ -224,7 +241,9 @@ static void decode_package_name(char* package_name) {
}
if (chip_model != 0) {
snprintf(package_name, CPUINFO_PACKAGE_NAME_MAX, "Apple A%" PRIu32 "%c", chip_model, suffix);
return true;
}
return false;
}

void cpuinfo_arm_mach_init(void) {
Expand Down Expand Up @@ -275,7 +294,8 @@ void cpuinfo_arm_mach_init(void) {
.core_start = i * cores_per_package,
.core_count = cores_per_package,
};
decode_package_name(packages[i].name);
if (!read_package_name_from_brand_string(packages[i].name))
decode_package_name_from_hw_machine(packages[i].name);
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Contributor Author

@dlenski dlenski May 22, 2024 •
edited
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The logic in decode_package_name_from_hw_machine has already become somewhat obsolete, which is why it makes sense to prefer read_package_name_from_brand_string wherever it succeeds on newer devices/OSes.

For example, the package in iPhone 15 Pro should be described as Apple A17 Pro, rather than simply A17 (which is what the current logic would show, according to the hw.machine values shown at: https://gist.github.com/adamawolf/3048717#file-apple_mobile_device_types-txt-L55-L56).

}

const uint32_t cpu_family = get_sys_info_by_name("hw.cpufamily");
Expand Down