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=-1.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED autolearn=ham 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 1D3A7C169C4 for ; Tue, 29 Jan 2019 10:09:44 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id D7F0620881 for ; Tue, 29 Jan 2019 10:09:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="japhrN2+" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D7F0620881 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender:Content-Type: Content-Transfer-Encoding:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=wuHTRU5JD0BUjj9t8HicWLD7AfER4KvrpntCZ4Eh0bE=; b=japhrN2+EK9/PuYKNy28rw9+R Qmll+uEXumfwWgXju8vzRLQd4X397kwbFk+GLT5i4dSudMZAQvRIciytHPLx76lE9nHcuWoLM7wGY iF0iAUZRLqNt34qaMjfQzsC68xTQSfo+JWjyjj8lFikRvxhK1DyevTEZ2on5mQ8z9t27nxR8rf5Cs QO/xLgxrSW5G13kBZOfUNrrIiDWkFma1eB2KzqLnkS3Z3kwUgPjGgOBoS2nWOOm8pXoz40MjnWyKO uakFbgBufRAbN+TRcPulwH+MWB8BOWEW/2JNHyz4/lwo8aLew7dF5xhqfLXgV1PSOFu9UZd6ARnHb lxToGq2GA==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1goQKr-0001sz-Cv; Tue, 29 Jan 2019 10:09:41 +0000 Received: from foss.arm.com ([217.140.101.70]) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1goQKn-0001rW-E3; Tue, 29 Jan 2019 10:09:38 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id A4A2D80D; Tue, 29 Jan 2019 02:09:34 -0800 (PST) Received: from [10.1.196.93] (en101.cambridge.arm.com [10.1.196.93]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 1C6903F59C; Tue, 29 Jan 2019 02:09:32 -0800 (PST) Subject: Re: [PATCH 1/2] arm64: Expose address bits (physical/virtual) via cpuinfo To: bhsharma@redhat.com, linux-arm-kernel@lists.infradead.org References: <1548709076-22317-1-git-send-email-bhsharma@redhat.com> <1548709076-22317-2-git-send-email-bhsharma@redhat.com> From: Suzuki K Poulose Message-ID: Date: Tue, 29 Jan 2019 10:09:31 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <1548709076-22317-2-git-send-email-bhsharma@redhat.com> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190129_020937_477689_7176049D X-CRM114-Status: GOOD ( 11.26 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mark.rutland@arm.com, Steve.Capper@arm.com, catalin.marinas@arm.com, ard.biesheuvel@linaro.org, will.deacon@arm.com, bhupesh.linux@gmail.com, kexec@lists.infradead.org Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Bupesh On 28/01/2019 20:57, Bhupesh Sharma wrote: > With ARMv8.2-LVA and LPA architecture extensions, arm64 hardware which > supports these extensions can support upto 52-bit virtual and 52-bit > physical addresses respectively. > > Since at the moment we enable the support of these extensions via CONFIG > flags, e.g. > - LPA via CONFIG_ARM64_PA_BITS_52, and > - LVA via CONFIG_ARM64_FORCE_52BIT > > The easiest way a user can determine the physical/virtual > addresses supported on the hardware, is via the '/proc/cpuinfo' > interface. Why do we need this information ? Btw, this keeps coming up all the time and the answer to this approach is always no. We cannot break the "unwritten" ABI of /proc/cpuinfo, again. See : https://patchwork.kernel.org/patch/8669301/ Suzuki _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel