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From: Marc Zyngier <maz@kernel.org>
To: Rongwei Wang <rongwei.wang@linux.alibaba.com>
Cc: catalin.marinas@arm.com, will@kernel.org, joey.gouly@arm.com,
	mark.rutland@arm.com, akpm@linux-foundation.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH RFC] arm64: improve display about CPU architecture in cpuinfo
Date: Mon, 07 Mar 2022 08:45:05 +0000	[thread overview]
Message-ID: <87h78a178u.wl-maz@kernel.org> (raw)
In-Reply-To: <20220307030417.22974-1-rongwei.wang@linux.alibaba.com>

On Mon, 07 Mar 2022 03:04:17 +0000,
Rongwei Wang <rongwei.wang@linux.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 by
a virtual address. You can't make that a '9'. Yet.

	M.

-- 
Without deviation from the norm, progress is not possible.

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

WARNING: multiple messages have this Message-ID (diff)
From: Marc Zyngier <maz@kernel.org>
To: Rongwei Wang <rongwei.wang@linux.alibaba.com>
Cc: catalin.marinas@arm.com, will@kernel.org, joey.gouly@arm.com,
	mark.rutland@arm.com, akpm@linux-foundation.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH RFC] arm64: improve display about CPU architecture in cpuinfo
Date: Mon, 07 Mar 2022 08:45:05 +0000	[thread overview]
Message-ID: <87h78a178u.wl-maz@kernel.org> (raw)
In-Reply-To: <20220307030417.22974-1-rongwei.wang@linux.alibaba.com>

On Mon, 07 Mar 2022 03:04:17 +0000,
Rongwei Wang <rongwei.wang@linux.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 by
a virtual address. You can't make that a '9'. Yet.

	M.

-- 
Without deviation from the norm, progress is not possible.

  parent reply	other threads:[~2022-03-07  8:46 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-03-07  3:04 [PATCH RFC] arm64: improve display about CPU architecture in cpuinfo Rongwei Wang
2022-03-07  3:04 ` Rongwei Wang
2022-03-07  8:43 ` Catalin Marinas
2022-03-07  8:43   ` Catalin Marinas
2022-03-07  8:45 ` Marc Zyngier [this message]
2022-03-07  8:45   ` Marc Zyngier
2022-03-07 12:13   ` Rongwei Wang
2022-03-07 12:13     ` Rongwei Wang
2022-03-07 12:23     ` Marc Zyngier
2022-03-07 12:23       ` Marc Zyngier
2022-03-07 16:48       ` Robin Murphy
2022-03-07 16:48         ` Robin Murphy
2022-03-07 19:30         ` Arnd Bergmann
2022-03-07 19:30           ` Arnd Bergmann
2022-03-07 20:05           ` Robin Murphy
2022-03-07 20:05             ` Robin Murphy
2022-03-08 17:18             ` Catalin Marinas
2022-03-08 17:18               ` Catalin Marinas
2022-03-08 17:47               ` Robin Murphy
2022-03-08 17:47                 ` Robin Murphy
2022-03-08 17:57             ` Russell King (Oracle)
2022-03-08 17:57               ` Russell King (Oracle)
2022-03-08 19:09               ` Robin Murphy
2022-03-08 19:09                 ` Robin Murphy
2022-03-08 17:55           ` Russell King (Oracle)
2022-03-08 17:55             ` Russell King (Oracle)

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