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From: Suzuki K Poulose <>
Subject: Re: [PATCH 1/2] arm64: Expose address bits (physical/virtual) via cpuinfo
Date: Tue, 29 Jan 2019 10:09:31 +0000
Message-ID: <> (raw)
In-Reply-To: <>

Hi Bupesh

On 28/01/2019 20:57, Bhupesh Sharma wrote:
> With ARMv8.2-LVA and LPA architecture extensions, arm64 hardware which
> supports these extensions can support upto 52-bit virtual and 52-bit
> physical addresses respectively.
> Since at the moment we enable the support of these extensions via CONFIG
> flags, e.g.
>   - LPA via CONFIG_ARM64_PA_BITS_52, and
> The easiest way a user can determine the physical/virtual
> addresses supported on the hardware, is via the '/proc/cpuinfo'
> interface.

Why do we need this information ?

Btw, this keeps coming up all the time and the answer to this approach is
always no. We cannot break the "unwritten" ABI of /proc/cpuinfo, again.
See :


linux-arm-kernel mailing list

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Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-28 20:57 [PATCH 0/2] arm64: Expose physical and virtual address capabilities to user-space Bhupesh Sharma
2019-01-28 20:57 ` [PATCH 1/2] arm64: Expose address bits (physical/virtual) via cpuinfo Bhupesh Sharma
2019-01-29 10:09   ` Suzuki K Poulose [this message]
2019-01-30 19:48     ` Bhupesh Sharma
2019-02-04 16:54       ` James Morse
2019-01-28 20:57 ` [PATCH 2/2] arm64: Expose PARange via ID_AA64MMFR0_EL1 and VARange via ID_AA64MMFR2_EL1 Bhupesh Sharma
2019-01-29 10:14   ` Suzuki K Poulose
2019-01-30 20:27     ` Bhupesh Sharma

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