Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753498AbcDBOFQ (ORCPT ); Sat, 2 Apr 2016 10:05:16 -0400 Received: from bh-25.webhostbox.net ([208.91.199.152]:36726 "EHLO bh-25.webhostbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751971AbcDBOFM (ORCPT ); Sat, 2 Apr 2016 10:05:12 -0400 Subject: Re: [PATCH] MIPS: Fix broken malta qemu To: Qais Yousef , Paul Burton , ralf@linux-mips.org References: <1458248889-24663-1-git-send-email-qsyousef@gmail.com> <20160401124852.GA5145@NP-P-BURTON> <56FFB8B7.8050607@gmail.com> Cc: Thomas Gleixner , linux-mips@linux-mips.org, linux-kernel@vger.kernel.org From: Guenter Roeck Message-ID: <56FFD191.70606@roeck-us.net> Date: Sat, 2 Apr 2016 07:05:05 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 MIME-Version: 1.0 In-Reply-To: <56FFB8B7.8050607@gmail.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Authenticated_sender: linux@roeck-us.net X-OutGoing-Spam-Status: No, score=-1.0 X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - bh-25.webhostbox.net X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - roeck-us.net X-Get-Message-Sender-Via: bh-25.webhostbox.net: authenticated_id: linux@roeck-us.net X-Authenticated-Sender: bh-25.webhostbox.net: linux@roeck-us.net X-Source: X-Source-Args: X-Source-Dir: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1560 Lines: 31 On 04/02/2016 05:19 AM, Qais Yousef wrote: > Hi Paul, > > On 01/04/2016 13:48, Paul Burton wrote: >> On Thu, Mar 17, 2016 at 09:08:09PM +0000, Qais Yousef wrote: >>> Malta defconfig compiles with GIC on. Hence when compiling for SMP it causes the >>> new IPI code to be activated. But on qemu malta there's no GIC causing a >>> BUG_ON(!ipidomain) to be hit in mips_smp_ipi_init(). >>> >>> Since in that configuration one can only run a single core SMP (!), skip IPI >>> initialisation if we detect that this is the case. It is a sensible behaviour >>> to introduce and should keep such possible configuration to run rather than die >>> hard unnecessarily. >> Hi Qais/Ralf, >> >> This patch is insufficient I'm afraid. It's entirely possible to use SMP >> with multiple VPEs in a single core on Malta boards that don't have a >> GIC - we have code handling IPIs in that case guarded by #ifdef >> CONFIG_MIPS_MT_SMP in arch/mips/mti-malta/malta-int.c. I think the >> BUG_ON needs to be removed entirely, unless that single-core multi-VPE >> IPI code is also converted to use an IPI irqdomain. >> > > I was under the impression that SMP is only supported under GIC and older forms of SMP are deprecated. > > I think the problem you're describing is different to the one this is trying to fix. The right fix for your issue is to make CONFIG_GENERIC_IRQ_IPI selected when CONFIG_MIPS_GIC && !CONFIG_MIPS_MT_SMP. > Didn't Paul say that his system doesn't have a GIC ? Are you saying that he can not (or no longer) run an image built for SMP on his system ? Guenter