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Fri, 16 Oct 2020 06:14:12 -0700 (PDT) Date: Fri, 16 Oct 2020 21:14:07 +0800 From: Leo Yan To: Suzuki Poulose 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-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201016_091415_879107_4B43C6F9 X-CRM114-Status: GOOD ( 14.88 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.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 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel