From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from galois.linutronix.de ([2a0a:51c0:0:12e:550::1]) by bombadil.infradead.org with esmtps (Exim 4.92 #3 (Red Hat Linux)) id 1hyYjR-0005UM-1A for kexec@lists.infradead.org; Fri, 16 Aug 2019 09:41:14 +0000 From: John Ogness Subject: Re: [RFC PATCH v4 9/9] printk: use a new ringbuffer implementation References: <20190807222634.1723-1-john.ogness@linutronix.de> <20190807222634.1723-10-john.ogness@linutronix.de> <20190816054651.GA4403@dhcp-128-65.nay.redhat.com> Date: Fri, 16 Aug 2019 11:40:54 +0200 In-Reply-To: <20190816054651.GA4403@dhcp-128-65.nay.redhat.com> (Dave Young's message of "Fri, 16 Aug 2019 13:46:51 +0800") Message-ID: <87y2ztwiqh.fsf@linutronix.de> MIME-Version: 1.0 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: Dave Young Cc: Andrea Parri , Petr Mladek , Kazuhito Hagio , Sergey Senozhatsky , Peter Zijlstra , Greg Kroah-Hartman , Brendan Higgins , linux-kernel@vger.kernel.org, Steven Rostedt , Sergey Senozhatsky , Simon Horman , Thomas Gleixner , Linus Torvalds , kexec@lists.infradead.org On 2019-08-16, Dave Young wrote: > John, can you cc kexec list for your later series? Sure. > On 08/08/19 at 12:32am, John Ogness wrote: >> This is a major change because the API (and underlying workings) of >> the new ringbuffer are completely different than the previous >> ringbuffer. Since there are several components of the printk >> infrastructure that use the ringbuffer API (console, /dev/kmsg, >> syslog, kmsg_dump), there are quite a few changes throughout the >> printk implementation. >> >> This is also a conservative change because it continues to use the >> logbuf_lock raw spinlock even though the new ringbuffer is lockless. >> >> The externally visible changes are: >> >> 1. The exported vmcore info has changed: >> >> - VMCOREINFO_SYMBOL(log_buf); >> - VMCOREINFO_SYMBOL(log_buf_len); >> - VMCOREINFO_SYMBOL(log_first_idx); >> - VMCOREINFO_SYMBOL(clear_idx); >> - VMCOREINFO_SYMBOL(log_next_idx); >> + VMCOREINFO_SYMBOL(printk_rb_static); >> + VMCOREINFO_SYMBOL(printk_rb_dynamic); > > I assumed this needs some userspace work in kexec, how did you test > them? I did not test any direct userspace access to the ringbuffer structures. > makedumpfile should need changes to dump the kernel log. > > Also kexec-tools includes a vmcore-dmesg.c to extrace dmesg from > /proc/vmcore. Thanks for the heads up. I'll take a look at it. The code changes should be straight forward. I expect there will need to be backwards compatibility. Perhaps it would check first for "printk_rb_*" then fallback to "log_*"? John Ogness _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec 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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 CE26BC3A59C for ; Fri, 16 Aug 2019 09:41:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A258120644 for ; Fri, 16 Aug 2019 09:41:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726995AbfHPJlt (ORCPT ); Fri, 16 Aug 2019 05:41:49 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:41840 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726765AbfHPJlt (ORCPT ); Fri, 16 Aug 2019 05:41:49 -0400 Received: from localhost ([127.0.0.1] helo=vostro.local) by Galois.linutronix.de with esmtp (Exim 4.80) (envelope-from ) id 1hyYjA-0006SV-I7; Fri, 16 Aug 2019 11:40:56 +0200 From: John Ogness To: Dave Young Cc: linux-kernel@vger.kernel.org, Peter Zijlstra , Petr Mladek , Sergey Senozhatsky , Steven Rostedt , Linus Torvalds , Greg Kroah-Hartman , Andrea Parri , Thomas Gleixner , Sergey Senozhatsky , Brendan Higgins , kexec@lists.infradead.org, Simon Horman , Kazuhito Hagio Subject: Re: [RFC PATCH v4 9/9] printk: use a new ringbuffer implementation References: <20190807222634.1723-1-john.ogness@linutronix.de> <20190807222634.1723-10-john.ogness@linutronix.de> <20190816054651.GA4403@dhcp-128-65.nay.redhat.com> Date: Fri, 16 Aug 2019 11:40:54 +0200 In-Reply-To: <20190816054651.GA4403@dhcp-128-65.nay.redhat.com> (Dave Young's message of "Fri, 16 Aug 2019 13:46:51 +0800") Message-ID: <87y2ztwiqh.fsf@linutronix.de> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.4 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019-08-16, Dave Young wrote: > John, can you cc kexec list for your later series? Sure. > On 08/08/19 at 12:32am, John Ogness wrote: >> This is a major change because the API (and underlying workings) of >> the new ringbuffer are completely different than the previous >> ringbuffer. Since there are several components of the printk >> infrastructure that use the ringbuffer API (console, /dev/kmsg, >> syslog, kmsg_dump), there are quite a few changes throughout the >> printk implementation. >> >> This is also a conservative change because it continues to use the >> logbuf_lock raw spinlock even though the new ringbuffer is lockless. >> >> The externally visible changes are: >> >> 1. The exported vmcore info has changed: >> >> - VMCOREINFO_SYMBOL(log_buf); >> - VMCOREINFO_SYMBOL(log_buf_len); >> - VMCOREINFO_SYMBOL(log_first_idx); >> - VMCOREINFO_SYMBOL(clear_idx); >> - VMCOREINFO_SYMBOL(log_next_idx); >> + VMCOREINFO_SYMBOL(printk_rb_static); >> + VMCOREINFO_SYMBOL(printk_rb_dynamic); > > I assumed this needs some userspace work in kexec, how did you test > them? I did not test any direct userspace access to the ringbuffer structures. > makedumpfile should need changes to dump the kernel log. > > Also kexec-tools includes a vmcore-dmesg.c to extrace dmesg from > /proc/vmcore. Thanks for the heads up. I'll take a look at it. The code changes should be straight forward. I expect there will need to be backwards compatibility. Perhaps it would check first for "printk_rb_*" then fallback to "log_*"? John Ogness