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=-2.4 required=3.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID, USER_AGENT_MUTT 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 12BAAC4321D for ; Wed, 22 Aug 2018 06:04:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C2209214C3 for ; Wed, 22 Aug 2018 06:03:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="ZGXejm+V" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C2209214C3 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728173AbeHVJ1T (ORCPT ); Wed, 22 Aug 2018 05:27:19 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:33510 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726696AbeHVJ1T (ORCPT ); Wed, 22 Aug 2018 05:27:19 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=yAmFxMvN3BD3bGlN5RcjnMnxoN1cKW/y/zvv9jkwmxE=; b=ZGXejm+VdZEAUiwQ7qXDhQcqK Xx5zqT4KD+wsH3w3O4y1KgZaqx9wgzJ+XYJGDCphnhf3ZYtJ7QUoFo2UukS85xlkWOhVDges0RT9A jYaKrlcTEHrtlzPvDz9CP1wFwSPhk/HPvELdGNlMOSdS174xN+uuuTePLBah4zkd+RvBIa1xstdWm fJE3rMT8tg6oxXcSt/5J9Atv/NTxlTSbDtyE/ExmTBWlyoR+LiKRExXJ66f4uhb/7W0WkjirvMnt8 vt2FJ9BCTp7zfpuxUhepjgPzcPO7/cSaMBxh0I9AVlctC53RsfKGWMn4dZ0dSKA3N3jXJE1T6pjwd 6emFGT02A==; Received: from hch by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1fsMFF-0007RA-Mx; Wed, 22 Aug 2018 06:03:53 +0000 Date: Tue, 21 Aug 2018 23:03:53 -0700 From: Christoph Hellwig To: Anup Patel Cc: Christoph Hellwig , Mark Rutland , Damien Le Moal , "palmer@sifive.com" , "linux-kernel@vger.kernel.org List" , Atish Patra , "linux-riscv@lists.infradead.org" , Thomas Gleixner Subject: Re: [RFC PATCH 3/5] RISC-V: Add cpu_operatios structure Message-ID: <20180822060353.GA27106@infradead.org> References: <1534377377-70108-1-git-send-email-atish.patra@wdc.com> <1534377377-70108-4-git-send-email-atish.patra@wdc.com> <20180821074826.GA28079@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.2 (2017-12-15) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 21, 2018 at 10:34:38PM +0530, Anup Patel wrote: > The cpu_operations is certainly required because SOC vendors will add > vendor-specific mechanism to selectively bringing-up CPUs/HARTs instead > of all CPUs entering Linux kernel simultaneously. In fact, we might also end-up > having CPU ON/OFF operations in SBI. Your forgot an essential part in your analysis: Right now we only have one single way to deal with cpu on/offlining, and that is the dummy WFI kind. Once other ways show up we can build proper infrastructure, but until then this is just a white elephant as we have no idea how these abstractions will look like. And my hope is that we'll just see new SBI calls, in which case we'll just need SBI and dummy version and can avoid all the indirect calls.