linux-kernel - Re: [PATCH v9] arm64: cpuinfo: Expose MIDR_EL1 and REVIDR

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Message-ID: <20160712110827.GB18408@arm.com>
Date:	Tue, 12 Jul 2016 12:08:28 +0100
From:	Will Deacon <will.deacon@....com>
To:	Suzuki K Poulose <suzuki.poulose@....com>
Cc:	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Steve Capper <steve.capper@...aro.org>,
	Catalin Marinas <catalin.marinas@....com>,
	Mark Rutland <mark.rutland@....com>
Subject: Re: [PATCH v9] arm64: cpuinfo: Expose MIDR_EL1 and REVIDR_EL1 to
 sysfs

On Fri, Jul 08, 2016 at 04:01:13PM +0100, Suzuki K Poulose wrote:
> From: Steve Capper <steve.capper@...aro.org>
> 
> 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 code generation.
> 
> This patch exposes these registers through sysfs:
> 
> /sys/devices/system/cpu/cpu$ID/regs/identification/midr_el1
> /sys/devices/system/cpu/cpu$ID/regs/identification/revidr_el1
> 
> 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.
> 
> Cc: Catalin Marinas <catalin.marinas@....com>
> Cc: Will Deacon <will.deacon@....com>
> Cc: Mark Rutland <mark.rutland@....com>
> Signed-off-by: Steve Capper <steve.capper@...aro.org>
> [ ABI documentation updates, hotplug notifiers, kobject changes ]
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>

Looks good to me, thanks for sticking with it:

Reviewed-by: Will Deacon <will.deacon@....com>

Will