[PATCH 9/9] arm64: Documentation - Expose CPU feature registers

Suzuki K Poulose Suzuki.Poulose at arm.com
Wed Nov 30 03:30:08 PST 2016


On 30/11/16 11:14, Siddhesh Poyarekar wrote:
> On Thursday 24 November 2016 07:10 PM, Suzuki K Poulose wrote:
>> + d) CPU Identification :
>> +    MIDR_EL1 is exposed to help identify the processor. On a
>> +    heterogeneous system, this could be racy (just like getcpu()). The
>> +    process could be migrated to another CPU by the time it uses the
>> +    register value, unless the CPU affinity is set. Hence, there is no
>> +    guarantee that the value reflects the processor that it is
>> +    currently executing on. The REVIDR is not exposed due to this
>> +    constraint, as REVIDR makes sense only in conjunction with the
>> +    MIDR. Alternately, MIDR_EL1 and REVIDR_EL1 are exposed via sysfs
>> +    at:
>> +
>> +    /sys/devices/system/cpu/cpu$ID/regs/identification/
>> +                                                  \- midr
>> +                                                  \- revidr
>> +
>
> This doesn't seem to be implemented in this patchset.

This is already available upstream.

Thanks
Suzuki

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