From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A733AC433EF for ; Mon, 7 Mar 2022 08:45:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232775AbiCGIqH (ORCPT ); Mon, 7 Mar 2022 03:46:07 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53258 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229715AbiCGIqG (ORCPT ); Mon, 7 Mar 2022 03:46:06 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CAD215F4F0 for ; Mon, 7 Mar 2022 00:45:10 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 72FC7B81031 for ; Mon, 7 Mar 2022 08:45:09 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 23F12C340E9; Mon, 7 Mar 2022 08:45:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1646642708; bh=KfwPer6wCVGGdXmDwvEpzQoyhCPiLUx4ifxQmfK2fcY=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=R6GdRCkzt8Chyf3myhr2bklzrA7sYbItQ+myOR4i0KU9ylwATZVvW4wlVemKZQ0+a pEcqWyAtIVHqu7INZ0zOWoijhM8CiqiKRYm8IxRqRvoPh52zZXPmlS4NLIk6BmdDRQ s6wAD1Z9E9fUuUDKe/bLk5yvS5kmhNPzfKcvoIVQPRxlf+GqaJdJUIXcbDh4Mzl/7s Yjuji3MG0z/tlNBpz2bDFiPtxdUf4A2ptf8iTgwDFfhgvjEgZFiSeMjtMuKdWVcHD8 PptGK9YE1UNdiyUCDaHcWlpuDuJRunnmKLX0evMKunKtdQe2yZHhDuOk2xbU7FPcWM R6iXQkOtCUE9w== Received: from sofa.misterjones.org ([185.219.108.64] helo=why.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1nR8zJ-00CgsF-NC; Mon, 07 Mar 2022 08:45:05 +0000 Date: Mon, 07 Mar 2022 08:45:05 +0000 Message-ID: <87h78a178u.wl-maz@kernel.org> From: Marc Zyngier To: Rongwei Wang 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 In-Reply-To: <20220307030417.22974-1-rongwei.wang@linux.alibaba.com> References: <20220307030417.22974-1-rongwei.wang@linux.alibaba.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/27.1 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: rongwei.wang@linux.alibaba.com, 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 X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 07 Mar 2022 03:04:17 +0000, Rongwei Wang 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.