[PATCH 1/2] arm64: Expose address bits (physical/virtual) via cpuinfo

Suzuki K Poulose suzuki.poulose at arm.com
Tue Jan 29 02:09:31 PST 2019


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
>   - LVA via CONFIG_ARM64_FORCE_52BIT
> 
> 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 :

https://patchwork.kernel.org/patch/8669301/


Suzuki



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