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 X-Spam-Level: X-Spam-Status: No, score=-0.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8AEDDECE58C for ; Fri, 11 Oct 2019 13:34:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6417F2084C for ; Fri, 11 Oct 2019 13:34:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="key not found in DNS" (0-bit key) header.d=codeaurora.org header.i=@codeaurora.org header.b="Sv9o6Sah"; dkim=fail reason="key not found in DNS" (0-bit key) header.d=codeaurora.org header.i=@codeaurora.org header.b="DTe4ww8/" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728312AbfJKNeK (ORCPT ); Fri, 11 Oct 2019 09:34:10 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:42344 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727709AbfJKNeK (ORCPT ); Fri, 11 Oct 2019 09:34:10 -0400 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id 399256119D; Fri, 11 Oct 2019 13:34:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1570800849; bh=qV7mshgmsk+PA+0O8tFTuDWkquelMqFFIB66c0mtXvw=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=Sv9o6SahDz0061+i8mzvszXlLhrR9qsDktrsbzlQ1yOt4cqgDdpPKMUYsS0AdRGjp TY256M8EkPlfijHqvkYOR/oac/5VmgJu+7guEZ1N1h9s+OE/f/AdAv8O3Kh7t1h06W WttHg8Ib4eIB5U/Jk/0U3IVaHNUJDbBgjcl5Uoyw= Received: from mail.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.codeaurora.org (Postfix) with ESMTP id 16D1261197; Fri, 11 Oct 2019 13:33:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1570800839; bh=qV7mshgmsk+PA+0O8tFTuDWkquelMqFFIB66c0mtXvw=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=DTe4ww8/Rj9UiVNqQ42aZF8hpaoSQgx/h5/neY7Ej2tjWAudV7pUqcK+NbO4M8q7f SvRvgGK+f2en3oE67UQ81aAsMgvJlvRB8AE4x3DdFbh0j6Vw6w0DGAXRxmuJyxaw2o zOL10H3tgjCyZkjlAazwa0jLMwumpydq57bekATE= MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Fri, 11 Oct 2019 19:03:58 +0530 From: Sai Prakash Ranjan To: Marc Gonzalez Cc: Mark Rutland , MSM , "Suzuki K. Poulose" , Catalin Marinas , Linux ARM , Ard Biesheuvel , linux-arm-kernel Subject: Re: Relax CPU features sanity checking on heterogeneous architectures In-Reply-To: References: <20191011105010.GA29364@lakrids.cambridge.arm.com> X-Priority: 1 (Highest) Message-ID: <8fb6dce8dcda42a14c1347295a812a0f@codeaurora.org> X-Sender: saiprakash.ranjan@codeaurora.org User-Agent: Roundcube Webmail/1.2.5 Sender: linux-arm-msm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org On 2019-10-11 16:39, Marc Gonzalez wrote: > On 11/10/2019 12:50, Mark Rutland wrote: > >> Before we make any changes, we need to check whether we do actually >> handle this variation in a safe way, and we need to consider what this >> means w.r.t. late CPU hotplug. >> >> Even if we can handle variation at boot time, once we've determined >> the >> set of system-wide features we cannot allow those to regress, and I >> believe we'll need new code to enforce that. I don't think it's >> sufficient to mark these as NONSTRICT, though we might do that with >> other changes. >> >> We shouldn't look at the part number at all here. We care about >> variation across CPUs regardless of whether this is big.LITTLE or some >> variation in tie-offs, etc. > > See also the "Unexpected variation in SYS_ID_AA64MMFR0_EL1" thread > from a year ago: (that was on msm8998) > > https://www.spinics.net/lists/arm-kernel/msg691242.html > I think, it was fixed by commit: 5717fe5ab38f ("arm64: cpufeature: Don't treat granule sizes as strict") Thanks, Sai -- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation