linux-kernel - Re: [PATCH RFC] arm64: improve display about CPU architecture in cpuinfo

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Date:   Mon, 7 Mar 2022 20:13:50 +0800
From:   Rongwei Wang <rongwei.wang@...ux.alibaba.com>
To:     Marc Zyngier <maz@...nel.org>
Cc:     catalin.marinas@....com, will@...nel.org, joey.gouly@....com,
        mark.rutland@....com, akpm@...ux-foundation.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFC] arm64: improve display about CPU architecture in
 cpuinfo



On 3/7/22 4:45 PM, Marc Zyngier wrote:
> On Mon, 07 Mar 2022 03:04:17 +0000,
> Rongwei Wang <rongwei.wang@...ux.alibaba.com> wrote:
>>
>> Now, it is unsuitable for both ARMv8 and ARMv9 to show a
>> fixed string "CPU architecture: 8" in /proc/cpuinfo.
> 
> Please read the various threads that have been going on over the past
> 10+ years about *why* we don't allow this sort of change (TL;DR: it
> breaks userspace, and we don't do that).
> 
> Also, there is no material difference between v8 and v9 that would be
> observable from userspace outside of the "Features:" line. And if that
> doesn't convince you, just think of '8' as the number of bytes used byI got your point. It seems that we can regard '8' as the number of 
bytes. But what make me do this is that 'CPU architecture: 8' is 
confusing, especially those responsible for testing.
And I believe that most people regard this '8' as ARMv8, maybe not.

In fact, I'm not sure it has potential ABI implications, so seek your 
advice.

Thanks!
> a virtual address. You can't make that a '9'. Yet.
> 
> 	M.
>