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=-5.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 86B71C433DF for ; Fri, 16 Oct 2020 13:14:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2E2C220848 for ; Fri, 16 Oct 2020 13:14:32 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="CpB0A1qL" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2407000AbgJPNOV (ORCPT ); Fri, 16 Oct 2020 09:14:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42626 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2404484AbgJPNOP (ORCPT ); Fri, 16 Oct 2020 09:14:15 -0400 Received: from mail-pf1-x444.google.com (mail-pf1-x444.google.com [IPv6:2607:f8b0:4864:20::444]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7A8E9C061755 for ; Fri, 16 Oct 2020 06:14:13 -0700 (PDT) Received: by mail-pf1-x444.google.com with SMTP id b26so1497482pff.3 for ; Fri, 16 Oct 2020 06:14:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=2v//XZb9addO+YnQGTuZ1rtYAQE5PbqfnjEF9yMyDoc=; b=CpB0A1qLkDsgmfvKFlr7UWapLdP1M00owIA2ts+xR/6P+6yK9aTnPfr/6RsH0lcJ+l rX5wPDmXPApN0QW7GUw/tRwsktOJgkS2wcU59h0u8CN8GJnM/Jtowgu1lUiN63H8RIKc wx3+f+RTXRcFKXiqmhSmnjdxEoPbQN1uj5++a3/5ThnGYl42h1HmtPI3AcKCgMbUrAjb vIIfwN2kfj2evVmwQ/OaNQDq4nl+TmJaTRNxpwtggZR8txOeD9QdwZhx2n1ZlKVL4k2R Gx3S4zpiFqE7TM9VVfbXNrvpt3gpBIWZeiJmmYFzZstDxfviyixPE2I7Gn+DXEbmaFli 3tcg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=2v//XZb9addO+YnQGTuZ1rtYAQE5PbqfnjEF9yMyDoc=; b=dqh09z+rpoadNFIlZAnM3rfH+JfRQYaIcqrzbqxfDXsCh6ajCRhmFMQXVc0vnd75RN FKtSTEhMuRQO2jX1hFov+DNcqBk5ncLHe3e8g2XHc0elzHsfOsrX+ftnm65VCfaqia6c ffY6oqmmQ9mVhdk9aENQHJYmAHsLJAH7AucR/TAdmftuBhlZhaLx9LGr7M7+Z+Ew5zVs it9SZrS9BI3KZUbGEnl+URSJiMsV5TFHhACG4BK6PteM6x8wKiRaO4vSwaQBboAmYd1N 4gsdNTRZghOquBCmdzcPrdQHNSufq1RmI4Upm7UHKt+WQ/I9ohXdJl/3HXxSVDd7exFb NZqQ== X-Gm-Message-State: AOAM531fiHz3YXwMw0N5OM0S2/IvilnKIwva6prPXnrnKpQ7ksLRfsbO lVv/rHmFlUdn2P6yU1zzFCP5lw== X-Google-Smtp-Source: ABdhPJwpBt1lWaerL/zTVz8TqRFSN2H2X1ZaeEtayOXScEJOTVGGH1v+RUnnCnoUuu2gcA9u1B5ljg== X-Received: by 2002:a63:1865:: with SMTP id 37mr3186358pgy.322.1602854052978; Fri, 16 Oct 2020 06:14:12 -0700 (PDT) Received: from leoy-ThinkPad-X240s ([64.120.119.108]) by smtp.gmail.com with ESMTPSA id e5sm3587979pjd.0.2020.10.16.06.14.09 (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Fri, 16 Oct 2020 06:14:12 -0700 (PDT) Date: Fri, 16 Oct 2020 21:14:07 +0800 From: Leo Yan To: Suzuki Poulose Cc: Sai Prakash Ranjan , Denis Nikitin , Mathieu Poirier , linux-arm-msm@vger.kernel.org, coresight@lists.linaro.org, linux-kernel@vger.kernel.org, Stephen Boyd , linux-arm-kernel@lists.infradead.org, Mike Leach Subject: Re: [PATCH] coresight: etm4x: Add config to exclude kernel mode tracing Message-ID: <20201016131407.GA31839@leoy-ThinkPad-X240s> References: <20201015124522.1876-1-saiprakash.ranjan@codeaurora.org> <20201015160257.GA1450102@xps15> <20201016072401.GC4646@leoy-ThinkPad-X240s> <20201016092450.GG4646@leoy-ThinkPad-X240s> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org On Fri, Oct 16, 2020 at 12:38:47PM +0100, Suzuki Kuruppassery Poulose wrote: [...] > > > What happens to the sysfs mode of tracing? For that we would still > > > need a config right to exclude kernel mode tracing completely. > > > > IIUC, sysfs mode and perf mode both can apply the same approach, the > > guest OS runs a thread context for the host, so when a guest OS is > > switched in or out, the hypervisor can save/restore the context for > > the guest OS; thus every guest OS will have its dedicated context and > > trace data ideally. > > I don't think Guest Context is something we can support as mentioned > above, at least for systems without sysreg access for ETMs (and virtualizing > ETRs is a different story !) Thanks for sharing thoughts, Suzuki. I missed the device virtulisation. Here should virtualize all devices (includes CoreSight ETM/funnel/ETR/ETF)? Or only need to virtualize ETRs? Obviously, this is a difficult task :) Thanks, Leo