From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758561AbcHDKRk (ORCPT ); Thu, 4 Aug 2016 06:17:40 -0400 Received: from pandora.armlinux.org.uk ([78.32.30.218]:52219 "EHLO pandora.armlinux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933481AbcHDKRf (ORCPT ); Thu, 4 Aug 2016 06:17:35 -0400 Date: Thu, 4 Aug 2016 11:07:48 +0100 From: Russell King - ARM Linux To: Guenter Roeck Cc: "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , Will Deacon Subject: Re: "Failed to create /dev/root: -14" after commit e6978e4bf1 ("ARM: save and reset the address limit when entering an exception") Message-ID: <20160804100748.GP1041@n2100.armlinux.org.uk> References: <57A15C41.6000804@roeck-us.net> <20160803083822.GI1041@n2100.armlinux.org.uk> <57A20896.30300@roeck-us.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <57A20896.30300@roeck-us.net> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Aug 03, 2016 at 08:07:02AM -0700, Guenter Roeck wrote: > On 08/03/2016 01:38 AM, Russell King - ARM Linux wrote: > >On Tue, Aug 02, 2016 at 07:51:45PM -0700, Guenter Roeck wrote: > >>Hi, > >> > >>I see the following crash when running a qemu arm 'kzm' runtime test with > >>the current mainline. > >>... > >>Failed to create /dev/root: -14 > >> > >>[ followed by panic ] > >> > >>A complete log file is at [1]. > > > >I think it's because of those undefined instructions you're hitting > >with the hw-breakpoint code... can you try the patch below please? > > > > arch/arm/kernel/entry-armv.S | 1 + > > 1 file changed, 1 insertion(+) > > > >diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S > >index bc5f50799d75..9f157e7c51e7 100644 > >--- a/arch/arm/kernel/entry-armv.S > >+++ b/arch/arm/kernel/entry-armv.S > >@@ -295,6 +295,7 @@ __und_svc_fault: > > bl __und_fault > > > > __und_svc_finish: > >+ get_thread_info tsk > > ldr r5, [sp, #S_PSR] @ Get SVC cpsr > > svc_exit r5 @ return from exception > > UNWIND(.fnend ) > > > > Yes, that fixes the problem. > > Assuming you'll create a patch: > > Tested-by: Guenter Roeck > > Does that need to be addressed in qemu, or is it a Linux bug ? It's a Linux bug provoked by qemu not implementing the hardware breakpoints. Well worth fixing in Linux. -- RMK's Patch system: http://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up according to speedtest.net.