Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933299AbbFJJ0G (ORCPT ); Wed, 10 Jun 2015 05:26:06 -0400 Received: from mail-la0-f44.google.com ([209.85.215.44]:36668 "EHLO mail-la0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932251AbbFJJZ4 (ORCPT ); Wed, 10 Jun 2015 05:25:56 -0400 MIME-Version: 1.0 In-Reply-To: <20150610090420.GA24882@pd.tnic> References: <1433848247-3550-1-git-send-email-kuleshovmail@gmail.com> <1433848293-5228-1-git-send-email-kuleshovmail@gmail.com> <1433865532.26331.108.camel@linux.intel.com> <20150609160727.GG22105@pd.tnic> <20150610090420.GA24882@pd.tnic> Date: Wed, 10 Jun 2015 15:25:54 +0600 Message-ID: Subject: Re: [PATCH v11 3/5] x86/earlyprintk: Allocate early log_buf as early as possible From: Alexander Kuleshov To: Borislav Petkov Cc: Andy Shevchenko , Andrew Morton , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , LKML , Greg Kroah-Hartman , Mark Rustad , Yinghai Lu Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1675 Lines: 36 2015-06-10 15:04 GMT+06:00 Borislav Petkov : > Yes, so this whole approach and what you're trying to achieve > seems kinda confusing and wrong. First of all, the early_printk() > machinery prints to a special console driver, i.e., I'm looking at the > registration fun in setup_early_printk(). > > So using early_printk() to print to dmesg is the wrong tool for the > job. Actually, if you want to do that, you can just as well use plain > printk() and try to make it work much earlier. Which is basically what > you did by using the printk_func per_cpu ptr, but that was hacky and > ugly. > > In order to do that right, you need to slow down first, think hard > and look hard and long at printk(), log_buf, the statically allocated > smaller __log_buf and the whole machinery behind it. Whether it can be > used that early or not. And to explain why it can or why it cannot in > your commit messages. Then test your stuff a *lot* on the hw you have > access to because printk() is not a joke. It needs to be very reliable > and to work. > That's right, I thought this too. But when you answered on 10th (https://lkml.org/lkml/2015/6/8/157) revision that you do not see earlyprintk messages in the dmesg output and I thought that he should be there, but didint research printk/log_buf and related stuff properly. I will try to learn all earlyprintk related things in more clear way and resend the patch. Thank you. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/