From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S967965AbeBOL44 (ORCPT ); Thu, 15 Feb 2018 06:56:56 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:52516 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S967902AbeBOL4x (ORCPT ); Thu, 15 Feb 2018 06:56:53 -0500 Subject: Re: [PATCH] s390/console: enable dummy console for vt To: Geert Uytterhoeven Cc: Bartlomiej Zolnierkiewicz , Farhan Ali , Linux Kernel Mailing List , Linux Fbdev development list , linux-s390 , Stefan Kristiansson , Tomi Valkeinen , Martin Schwidefsky , DRI Development , Chen Liqin , Lennox Wu , Jeff Dike , Richard Weinberger , uml-devel , Thomas Huth References: <2324e2cc-ff55-4d57-2807-c7f72f9ea0ca@de.ibm.com> <20180215111423.96598-1-borntraeger@de.ibm.com> From: Christian Borntraeger Date: Thu, 15 Feb 2018 12:56:44 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 x-cbid: 18021511-0020-0000-0000-000003F5F019 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18021511-0021-0000-0000-0000428882D3 Message-Id: <13a674d4-68d5-6fb4-5902-26c6b631b596@de.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2018-02-15_05:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1802150149 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/15/2018 12:26 PM, Geert Uytterhoeven wrote: > Hi Christian, > > On Thu, Feb 15, 2018 at 12:14 PM, Christian Borntraeger > wrote: >> To enable the virtual terminal layer with virtio-gpu, we need to >> provide the dummy console. This console is hidden behind CONFIG_IOMEM >> via the graphics support. Instead of fully enabling the graphic >> drivers lets just provide a Kconfig option for the dummy console. >> >> Signed-off-by: Christian Borntraeger >> --- >> New version: instead of moving around the graphic and console stuff, >> let's just keep an s390 specific variant of CONFIG_DUMMY_CONSOLE >> arch/s390/Kconfig | 5 +++++ >> 1 file changed, 5 insertions(+) >> >> diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig >> index cbe1d978693a..a69690f616f3 100644 >> --- a/arch/s390/Kconfig >> +++ b/arch/s390/Kconfig >> @@ -952,6 +952,11 @@ config S390_HYPFS_FS >> >> source "arch/s390/kvm/Kconfig" >> >> +config DUMMY_CONSOLE >> + bool >> + depends on VT >> + default y >> + >> config S390_GUEST >> def_bool y >> prompt "s390 support for virtio devices" > > Really? > > You already have your own copy of HAS_IOMEM, which makes it hard for > people to track which one applies where. > I am open for better suggestions. One idea that I had was to reverse the logic in s390 (and use the common code HAS_IOMEM) like diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig index cbe1d978693a..123dd593ea20 100644 --- a/arch/s390/Kconfig +++ b/arch/s390/Kconfig @@ -715,8 +715,8 @@ endif # PCI config PCI_DOMAINS def_bool PCI -config HAS_IOMEM - def_bool PCI +config NO_IOMEM + def_bool y if !PCI config IOMMU_HELPER def_bool PCI This would enable CONFIG_VT and also CONFIG_DUMMY_CONSOLE as long as PCI is enabled. If DUMMY_CONSOLE is not enabled (e.g. due to missing PCI), we get a crash in the VT layer as conswitchp is then null. Somewhat tricky.