Re: [PATCH v4] arm64: cpuinfo: Expose MIDR_EL1 and REVIDR_EL1 to sysfs

[Russell King - ARM Linux]

On Mon, Jun 13, 2016 at 06:08:09PM +0100, Suzuki K Poulose wrote:
> From: Steve Capper <steve.capper@xxxxxxxxxx>
> 
> 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.

So there's no confusion, I've historically said no on 32-bit ARM to
exposing the MIDR to userspace, and my position on that for 32-bit
ARM has not changed.

-- 
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