From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sai Prakash Ranjan Subject: Re: [PATCH 0/6] Tracing register accesses with pstore and dynamic debug Date: Sun, 21 Oct 2018 10:29:17 +0530 Message-ID: <92075d3d-1ea9-d746-384a-1b61ceefcb70@codeaurora.org> References: <20181020052535.GA155509@joelaf.mtv.corp.google.com> <1d3ddbe3-d3ac-aa3e-fc9e-36739ddd0c91@codeaurora.org> <20181020162719.GA49955@joelaf.mtv.corp.google.com> <15ec736d-bd54-5519-4b99-47dd161bc556@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <15ec736d-bd54-5519-4b99-47dd161bc556@codeaurora.org> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Joel Fernandes Cc: Tom Zanussi , Catalin Marinas , Will Deacon , Vivek Gautam , Prasad Sodagudi , Ingo Molnar , tsoni@codeaurora.org, Anton Vorontsov , Ingo Molnar , Sibi Sankar , Laura Abbott , devicetree@vger.kernel.org, Kees Cook , Arnd Bergmann , linux-arm-msm@vger.kernel.org, Steven Rostedt , Jason Baron , Rob Herring , Tingwei Zhang , linux-arm-kernel@lists.infradead.org, Tony Luck , Rajendra List-Id: linux-arm-msm@vger.kernel.org On 10/21/2018 9:16 AM, Sai Prakash Ranjan wrote: > On 10/20/2018 9:57 PM, Joel Fernandes wrote: >> On Sat, Oct 20, 2018 at 12:02:37PM +0530, Sai Prakash Ranjan wrote: >>> On 10/20/2018 10:55 AM, Joel Fernandes wrote: >>>> On Sun, Sep 09, 2018 at 01:57:01AM +0530, Sai Prakash Ranjan wrote: >>>>> Hi, >>>>> >>>>> This patch series adds Event tracing support to pstore and is >>>>> continuation >>>>> to the RFC patch introduced to add a new tracing facility for register >>>>> accesses called Register Trace Buffer(RTB). Since we decided to not >>>>> introduce >>>>> a separate framework to trace register accesses and use existing >>>>> framework >>>>> like tracepoints, I have moved from RFC. Details of the RFC in link >>>>> below: >>>>> >>>>> Link: >>>>> https://lore.kernel.org/lkml/cover.1535119710.git.saiprakash.ranjan@codeaurora.org/ >>>>> >>>>> >>>>> MSR tracing example given by Steven was helpful in using >>>>> tracepoints for >>>>> register accesses instead of using separate trace. But just having >>>>> these >>>>> IO traces would not help much unless we could have them in some >>>>> persistent >>>>> ram buffer for debugging unclocked access or some kind of bus hang >>>>> or an >>>>> unexpected reset caused by some buggy driver which happens a lot >>>>> during >>>>> initial development stages. By analyzing the last few entries of >>>>> this buffer, >>>>> we could identify the register access which is causing the issue. >>>> >>>> Hi Sai, >>>> >>>> I wanted to see if I could make some time to get your patches >>>> working. We are >>>> hitting usecases that need something like this as well. Basically >>>> devices >>>> hanging and then the ramdump does not tell us much, so in this case >>>> pstore >>>> events can be really helpful. This usecase came up last year as well. >>>> >>>> Anyway while I was going through your patches, I cleaned up some >>>> pstore code >>>> as well and I have 3 more patches on top of yours for this clean up. >>>> I prefer >>>> we submit the patches together and sync our work together so that >>>> there is >>>> least conflict. >>>> >>>> Here's my latest tree: >>>> https://github.com/joelagnel/linux-kernel/commits/pstore-events >>>> (note that I have only build tested the patches since I just wrote >>>> them and >>>> its quite late in the night here ;-)) >>>> >>> >>> Hi Joel, >>> >>> Thanks for looking into this. Sure, I will be happy to sync up with >>> you on >> >> Thanks. And added a fourth patch in the tree too. >> >>> this. I can test your additional patches on top of my pstore patches. >>> BTW, >>> I'm still stuck at copying binary record into pstore and then extract it >>> during read time. Seems like I'm missing something. >> >> Sure, push your latest somewhere and let me know. I'll try to get you >> unstuck. >> > > Thanks Joel, I will push my changes and let you know in some time. > Hi Joel, Here's my tree: https://github.com/saiprakash-ranjan/linux/commits/pstore-events I have one patch extra on top of your patches. Nothing much on binary record storage in this patch, only removed kmalloc in pstore event call to avoid loop. Thanks, Sai -- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation