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SubjectRe: [PATCH v3 24/24] arm64: cpuinfo: Expose MIDR_EL1 and REVIDR_EL1 to sysfs
On 13/10/15 18:22, Suzuki K. Poulose wrote:
> From: Steve Capper <>
> It can be useful for JIT software to be aware of MIDR_EL1 and
> REVIDR_EL1 to ascertain the presence of any core errata that could
> affect codegen.
> This patch exposes these registers through sysfs:
> /sys/devices/system/cpu/cpu$ID/identification/midr
> /sys/devices/system/cpu/cpu$ID/identification/revidr
> where $ID is the cpu number. For big.LITTLE systems, one can have a
> mixture of cores (e.g. Cortex A53 and Cortex A57), thus all CPUs need
> to be enumerated.
> If the kernel does not have valid information to populate these entries
> with, an empty string is returned to userspace.

For the record:

> Signed-off-by: Steve Capper <>
[ Added error code for cpus !present in show_xxx_name ]
> Signed-off-by: Suzuki K. Poulose <>


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