From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mx1.redhat.com ([209.132.183.28]) by bombadil.infradead.org with esmtps (Exim 4.92 #3 (Red Hat Linux)) id 1hyVBx-0002Js-KI for kexec@lists.infradead.org; Fri, 16 Aug 2019 05:54:26 +0000 Date: Fri, 16 Aug 2019 13:54:16 +0800 From: Dave Young Subject: Re: [RFC PATCH v4 9/9] printk: use a new ringbuffer implementation Message-ID: <20190816055416.GA4460@dhcp-128-65.nay.redhat.com> References: <20190807222634.1723-1-john.ogness@linutronix.de> <20190807222634.1723-10-john.ogness@linutronix.de> <20190816054651.GA4403@dhcp-128-65.nay.redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190816054651.GA4403@dhcp-128-65.nay.redhat.com> 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: John Ogness 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 , David Woodhouse , Linus Torvalds , kexec@lists.infradead.org On 08/16/19 at 01:46pm, Dave Young wrote: > John, can you cc kexec list for your later series? > > 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? > > makedumpfile should need changes to dump the kernel log. > > Also kexec-tools includes a vmcore-dmesg.c to extrace dmesg from > /proc/vmcore. > > > > > 2. For the CONFIG_PPC_POWERNV powerpc platform, kernel log buffer > > registration is no longer available because there is no longer > > a single contigous block of memory to represent all of the > > ringbuffer. > > > > Signed-off-by: John Ogness > > --- > > arch/powerpc/platforms/powernv/opal.c | 22 +- > > include/linux/kmsg_dump.h | 6 +- > > include/linux/printk.h | 12 - > > kernel/printk/printk.c | 745 ++++++++++++++------------ > > kernel/printk/ringbuffer.h | 24 + > > 5 files changed, 415 insertions(+), 394 deletions(-) > > [snip] Seems kexec list has 40k limitation for msg body. Simon and David, maybe it is too small? Thanks Dave _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec