From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754295AbdEQOqA (ORCPT ); Wed, 17 May 2017 10:46:00 -0400 Received: from mail-pf0-f176.google.com ([209.85.192.176]:34472 "EHLO mail-pf0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752968AbdEQOp7 (ORCPT ); Wed, 17 May 2017 10:45:59 -0400 Subject: Re: Question regarding RT patches for ARM To: Fawad Lateef Cc: GuJiangfei , Linux Kernel Mailing List , kernelnewbies , linux-rt-users@vger.kernel.org References: <3aa42082.b247.15c0c29ca5e.Coremail.qiledexin@163.com> <646e1a43-78a7-3d04-ee29-1299b7d9d4d8@nelint.com> From: Eric Nelson Message-ID: Date: Wed, 17 May 2017 07:45:39 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.1.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Fawad, On 05/17/2017 06:40 AM, Fawad Lateef wrote: > On 15 May 2017 at 16:20, Fawad Lateef wrote: >> Hi Eric, >> On 15 May 2017 at 16:12, Eric Nelson wrote: >>> Hi Fawad, >>> >>>> 发自网易邮箱大师 >>>> On 05/15/2017 20:44, Fawad Lateef wrote: >>>> >>>> Hi All, >>>> >>>> I am working on custom i.MX6 quad hardware and using RT patches for >>>> almost latest stable kernel 4.9 and facing some weird system stall OR >>>> 'unhandled page fault - exceptions'. >>>> >>> >>> I'm not sure about the unhandled page fault, but the stalls may be >>> because of the SDMA driver. >>> >>> See this patch in the Freescale/NXP community for kernel 4.1: >>> https://github.com/Freescale/meta-freescale/blob/master/recipes-kernel/linux/linux-fslc-imx-rt/0003-Work-around-CPU-stalls-in-the-imx-sdma-driver.patch >>> >> >> Thanks for the patch link. I will give it a try. > > Talked to hardware manufacturer and they applied the patch. > > Still that SDMA is only used for NOR flash and only u-boot and its > environment are stored in nor flash. So not sure if that is going to > help in any case. > SDMA is used for much more than NOR flash (SSI, USB, and sometimes UARTs). > So I would really like few more suggestions OR confirmations about ARM > (cortex-A9 based imx6) (preemept)-RT support/patches are stable and > can be used for final products. > I don't have any experience with the RT patches on 4.9 or later kernels, but do know that they're being used on i.MX6 with the vendor kernels (3.10.x, 4.1.x). I believe Alison Chaiken mentioned using them with 4.9 kernels: http://elinux.org/images/4/42/IRQs-_the_Hard%2C_the_Soft%2C_the_Threaded_and_the_Preemptible.pdf https://www.youtube.com/watch?v=-pehAzaP1eg&feature=youtu.be&list=PLbzoR-pLrL6pRFP6SOywVJWdEHlmQE51q Regards, Eric