From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758395AbcATVgO (ORCPT ); Wed, 20 Jan 2016 16:36:14 -0500 Received: from mail-oi0-f42.google.com ([209.85.218.42]:36694 "EHLO mail-oi0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751773AbcATVgK (ORCPT ); Wed, 20 Jan 2016 16:36:10 -0500 Subject: Re: Boot problem on PPC with 4.4-git - Bisected to commit 21266be To: Dan Williams References: <569FE7A9.7090902@lwfinger.net> Cc: LKML From: Larry Finger Message-ID: <569FFDC7.8020002@lwfinger.net> Date: Wed, 20 Jan 2016 15:36:07 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/20/2016 02:33 PM, Dan Williams wrote: > On Wed, Jan 20, 2016 at 12:16 PM, Dan Williams wrote: >> On Wed, Jan 20, 2016 at 12:08 PM, Dan Williams wrote: >>> On Wed, Jan 20, 2016 at 12:01 PM, Larry Finger >>> wrote: >>>> My PowerBook G4 Aluminum with a 32-bit PPC processor fails to boot for the >>>> 4.4-git series. The problem was bisected to commit 21266be. It took a while >>>> to figure out why a commit that only rearranges the Kconfig files could >>>> cause the problem. >>>> >>>> The answer came when I read the commit message for 90a545e98126 and saw that >>>> "Recompiling with CONFIG_IO_STRICT_DEVMEM=n" might be necessary. After I >>>> made that change, the system boots. >>>> >>>> If it is the graphics hardware driver at fault, the VGA controller is listed >>>> as an ATI RV350 [Mobility Radeon 9600 M10] with PCI ID 1002:4350. It uses >>>> radeon as the driver. >>>> >>>> I'm not sure if this is a bug in the configuration, but I know that >>>> selecting the default answer to all the new configuration parameters leaves >>>> me with a machine that is unbootable. >>> >>> I agree that the default configuration should remain bootable. I'll >>> send a change that does not force that default. >>> >>> Thanks for the report and sorry for the inconvenience. >> >> Are you sure that the bisect is pointing to "21266be9ed54 arch: >> consolidate CONFIG_STRICT_DEVM in lib/Kconfig.debug" and not >> "90a545e98126 restrict /dev/mem to idle io memory ranges"? The >> default for CONFIG_STRICT_DEVM should be unchanged in 21266be9ed54, >> it's not until 90a545e98126 that I would expect a behavior change. > > Sorry for the mail flurry... if you can verify that the following > change resolves this problem I'll send it up: > > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > index f75a33f29f6e..7d0b49c536c5 100644 > --- a/lib/Kconfig.debug > +++ b/lib/Kconfig.debug > @@ -1919,7 +1919,6 @@ config STRICT_DEVMEM > config IO_STRICT_DEVMEM > bool "Filter I/O access to /dev/mem" > depends on STRICT_DEVMEM > - default STRICT_DEVMEM > ---help--- > If this option is disabled, you allow userspace (root) access to all > io-memory regardless of whether a driver is actively using that That isn't quite right. I added that patch, and restored the 4.4.0 configuration. That one has "CONFIG_STRICT_DEVM=y". After I ran "make oldconfig", CONFIG_STRICT_DEVM was still set, which kills rebooting. When I repeated the process, but removed the CONFIG_STRICT_DEVM line from .config before I ran "make oldconfig", then I got a bootable configuration. It seems that once STRICT_DEVM is yes, only a "make menuconfig", or equivalent, will let you turn it off. Larry