From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751902AbbJLRBa (ORCPT ); Mon, 12 Oct 2015 13:01:30 -0400 Received: from eu-smtp-delivery-143.mimecast.com ([146.101.78.143]:37114 "EHLO eu-smtp-delivery-143.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751219AbbJLRB3 convert rfc822-to-8bit (ORCPT ); Mon, 12 Oct 2015 13:01:29 -0400 Subject: Re: [PATCH v2 07/22] arm64: Keep track of CPU feature registers To: mark.rutland@arm.com References: <1444064531-25607-1-git-send-email-suzuki.poulose@arm.com> <1444064531-25607-8-git-send-email-suzuki.poulose@arm.com> <20151007171621.GD17192@e104818-lin.cambridge.arm.com> <56163D7F.4000003@arm.com> <20151008150346.GK17192@e104818-lin.cambridge.arm.com> Cc: Catalin Marinas , Vladimir.Murzin@arm.com, steve.capper@linaro.org, ard.biesheuvel@linaro.org, marc.zyngier@arm.com, andre.przywara@arm.com, will.deacon@arm.com, linux-kernel@vger.kernel.org, edward.nevill@linaro.org, aph@redhat.com, james.morse@arm.com, dave.martin@arm.com, linux-arm-kernel@lists.infradead.org From: "Suzuki K. Poulose" Message-ID: <561BE765.1080409@arm.com> Date: Mon, 12 Oct 2015 18:01:25 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.2.0 MIME-Version: 1.0 In-Reply-To: <20151008150346.GK17192@e104818-lin.cambridge.arm.com> X-OriginalArrivalTime: 12 Oct 2015 17:01:26.0147 (UTC) FILETIME=[A16E6530:01D1050F] X-MC-Unique: yjlBPG5rTXS6ljvPzFYjcQ-1 Content-Type: text/plain; charset=WINDOWS-1252; format=flowed Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/10/15 16:03, Catalin Marinas wrote: > On Thu, Oct 08, 2015 at 10:55:11AM +0100, Suzuki K. Poulose wrote: ... > > So we have three types of fields in these registers: > > a) features defined but not something we care about in Linux > b) reserved fields > c) features important to Linux > > I guess for (a), Linux may not even care if they don't match (though we > need to be careful which fields we ignore). As for (b), even if they > differ, since we don't know the meaning at this point, I think we should > just ignore them. If, for example, they add a feature that Linux doesn't > care about, they practically fall under the (a) category. > > Regarding exposing reserved CPUID fields to user, I assume we would > always return 0. Mark, Do you have any comments on this ? The list I have here is what you came up with in SANITY checks. Thanks Suzuki