From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753132AbaIODeQ (ORCPT ); Sun, 14 Sep 2014 23:34:16 -0400 Received: from mx1.redhat.com ([209.132.183.28]:25212 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752277AbaIODeO (ORCPT ); Sun, 14 Sep 2014 23:34:14 -0400 Date: Mon, 15 Sep 2014 11:33:55 +0800 From: Dave Young To: Greg KH Cc: Matt Fleming , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, Andrew Morton , matt.fleming@intel.com, linux-efi@vger.kernel.org, linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, devel@acpica.org, lenb@kernel.org, rafael.j.wysocki@intel.com, robert.moore@intel.com, stable@vger.kernel.org Subject: Re: [PATCH RFC] x86 early_ioremap: increase FIX_BTMAPS_SLOTS to 8 Message-ID: <20140915033355.GB2700@darkstar.nay.redhat.com> References: <20140826090641.GA16550@darkstar.nay.redhat.com> <20140914141412.GJ18582@console-pimps.org> <20140915023805.GA2700@darkstar.nay.redhat.com> <20140915024205.GA2561@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140915024205.GA2561@kroah.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/14/14 at 07:42pm, Greg KH wrote: > On Mon, Sep 15, 2014 at 10:38:05AM +0800, Dave Young wrote: > > On 09/14/14 at 03:14pm, Matt Fleming wrote: > > > On Tue, 26 Aug, at 05:06:41PM, Dave Young wrote: > > > > 3.16 kernel boot fail with earlyprintk=efi, it keeps scrolling at the > > > > bottom line of screen. > > > > > > > > Bisected, the first bad commit is below: > > > > commit 86dfc6f339886559d80ee0d4bd20fe5ee90450f0 > > > > Author: Lv Zheng > > > > Date: Fri Apr 4 12:38:57 2014 +0800 > > > > > > > > ACPICA: Tables: Fix table checksums verification before installation. > > > > > > [...] > > > > > > > Quote reply from Lv.zheng about the early ioremap slot usage in this case: > > > > > > > > """ > > > > In early_efi_scroll_up(), 2 mapping entries will be used for the src/dst screen buffer. > > > > In drivers/acpi/acpica/tbutils.c, we've improved the early table loading code in acpi_tb_parse_root_table(). > > > > We now need 2 mapping entries: > > > > 1. One mapping entry is used for RSDT table mapping. Each RSDT entry contains an address for another ACPI table. > > > > 2. For each entry in RSDP, we need another mapping entry to map the table to perform necessary check/override before installing it. > > > > > > > > When acpi_tb_parse_root_table() prints something through EFI earlyprintk console, we'll have 4 mapping entries used. > > > > The current 4 slots setting of early_ioremap() seems to be too small for such a use case. > > > > """ > > > > > > > > Thus increase the slot to 8 in this patch to fix this issue. > > > > boot-time mappings become 512 page with this patch. > > > > > > This analysis and solution makes sense to me, but I was really hoping > > > for one of the x86 maintainers to ACK the below patch. I'm happy to take > > > it through the EFI tree if it's not picked up into tip meanwhile. > > > > > > Also, Dave, it sounds like this should be tagged for stable if the bug > > > has been around since v3.16? > > > > Matt, yes, it should be a stable issue, ccing Greg and stable list. > > > > This is not the correct way to submit patches for inclusion in the > stable kernel tree. Please read Documentation/stable_kernel_rules.txt > for how to do this properly. > > Frankly I did not know the exact work flow about stable patches. Thanks for pointing me the documentation. I was just assuming I should cc your guys about the issues which could be stable candidate even though it has not been accepted now, so it can get noticed by stable people. Thanks Dave