From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936526AbeBUQju (ORCPT ); Wed, 21 Feb 2018 11:39:50 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:36572 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932674AbeBUQjs (ORCPT ); Wed, 21 Feb 2018 11:39:48 -0500 Subject: Re: [PATCH v3 1/3] Kconfig : Remove HAS_IOMEM dependency for Graphics support To: Christian Borntraeger , Cornelia Huck Cc: Thomas Huth , linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, linux-fbdev@vger.kernel.org, geert@linux-m68k.org, tomi.valkeinen@ti.com, b.zolnierkie@samsung.com References: <2beec7645bac82e7bdef4f6df0b9f4fe28696575.1519053920.git.alifm@linux.vnet.ibm.com> <6cae85dc-76d5-1b92-ab13-a5e441eb84a0@linux.vnet.ibm.com> <20180221113217.11bb1c69.cohuck@redhat.com> <1f8907d4-c4a3-d41b-8834-679dcc85de4a@de.ibm.com> <5dfa9213-0e63-54d0-8700-1ced4efd4c28@redhat.com> <20180221130755.17d15f89.cohuck@redhat.com> <6c1daae4-e1f6-5627-9023-f03d986c5639@de.ibm.com> From: Farhan Ali Date: Wed, 21 Feb 2018 11:39:12 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 MIME-Version: 1.0 In-Reply-To: <6c1daae4-e1f6-5627-9023-f03d986c5639@de.ibm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 x-cbid: 18022116-0048-0000-0000-0000023CF49D X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00008570; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000254; SDB=6.00993029; UDB=6.00504548; IPR=6.00772374; MB=3.00019675; MTD=3.00000008; XFM=3.00000015; UTC=2018-02-21 16:39:14 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18022116-0049-0000-0000-0000443525D4 Message-Id: <2170dce6-4456-3ab6-d07c-2169d99c4173@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2018-02-21_06:,, 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-1802210203 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/21/2018 07:11 AM, Christian Borntraeger wrote: > > > On 02/21/2018 01:07 PM, Cornelia Huck wrote: > [...] >>>> But if you need to enable PCI to get IOMEM, I wonder why this patch here >>>> is needed at all? The Graphics menu / VT dummy console should be >>>> available in the config if IOMEM is enabled anyway? >>> >>> That is a good question. With CONFIG_PCI=y I can select virtio-gpu and dummy-console. >>> IIRC the issue was that with patch 3 we can have the situation where we have >>> CONFIG_VT = y and CONFIG_DUMMY_CONSOLE=n and this will crash early during boot as >>> conswitchp is NULL. Yes, VT layer initializes very early in the boot process and looks for a console. If it can't find any it will crash. I believe that was the whole point of having the dummy console. >> >> So in practice, CONFIG_VT depends on "there's a console available, even >> if it's only the dummy one"? > > Yes. Maybe we should simple move dummy_console outside of drivers/video/console/Kconfig > into something that is always available. > I agree, but where should it go? consoles are kinda tightly tied to video/Graphics Support. >> >>> This patches goal was to always enable dummy console even without >>> PCI, but it obviously fails to do so. >> This patch should enable the dummy console even without PCI but we won't have DRM/Virtio GPU. >> OTOH, the dummy console really should not depend on anything, as it is >> only doing dummy things. >> >>> >>> So what about allowing CONFIG_VT on s390 only if we have PCI? >>> >>> >>> diff --git a/drivers/tty/Kconfig b/drivers/tty/Kconfig >>> index 84810075a6a0..1c7fe09d6f90 100644 >>> --- a/drivers/tty/Kconfig >>> +++ b/drivers/tty/Kconfig >>> @@ -11,7 +11,7 @@ if TTY >>> >>> config VT >>> bool "Virtual terminal" if EXPERT >>> - depends on !UML >>> + depends on !UML && (!S390 || PCI) >>> select INPUT >>> default y >>> ---help--- >>> >> >> Would cover your use case, but feels wrong to me... config dependencies >> aren't fun :/ >> From mboxrd@z Thu Jan 1 00:00:00 1970 From: Farhan Ali Date: Wed, 21 Feb 2018 16:39:12 +0000 Subject: Re: [PATCH v3 1/3] Kconfig : Remove HAS_IOMEM dependency for Graphics support Message-Id: <2170dce6-4456-3ab6-d07c-2169d99c4173@linux.vnet.ibm.com> References: <2beec7645bac82e7bdef4f6df0b9f4fe28696575.1519053920.git.alifm@linux.vnet.ibm.com> <6cae85dc-76d5-1b92-ab13-a5e441eb84a0@linux.vnet.ibm.com> <20180221113217.11bb1c69.cohuck@redhat.com> <1f8907d4-c4a3-d41b-8834-679dcc85de4a@de.ibm.com> <5dfa9213-0e63-54d0-8700-1ced4efd4c28@redhat.com> <20180221130755.17d15f89.cohuck@redhat.com> <6c1daae4-e1f6-5627-9023-f03d986c5639@de.ibm.com> In-Reply-To: <6c1daae4-e1f6-5627-9023-f03d986c5639@de.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit List-Archive: List-Post: To: Christian Borntraeger , Cornelia Huck Cc: Thomas Huth , linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, linux-fbdev@vger.kernel.org, geert@linux-m68k.org, tomi.valkeinen@ti.com, b.zolnierkie@samsung.com List-ID: On 02/21/2018 07:11 AM, Christian Borntraeger wrote: > > > On 02/21/2018 01:07 PM, Cornelia Huck wrote: > [...] >>>> But if you need to enable PCI to get IOMEM, I wonder why this patch here >>>> is needed at all? The Graphics menu / VT dummy console should be >>>> available in the config if IOMEM is enabled anyway? >>> >>> That is a good question. With CONFIG_PCI=y I can select virtio-gpu and dummy-console. >>> IIRC the issue was that with patch 3 we can have the situation where we have >>> CONFIG_VT = y and CONFIG_DUMMY_CONSOLE=n and this will crash early during boot as >>> conswitchp is NULL. Yes, VT layer initializes very early in the boot process and looks for a console. If it can't find any it will crash. I believe that was the whole point of having the dummy console. >> >> So in practice, CONFIG_VT depends on "there's a console available, even >> if it's only the dummy one"? > > Yes. Maybe we should simple move dummy_console outside of drivers/video/console/Kconfig > into something that is always available. > I agree, but where should it go? consoles are kinda tightly tied to video/Graphics Support. >> >>> This patches goal was to always enable dummy console even without >>> PCI, but it obviously fails to do so. >> This patch should enable the dummy console even without PCI but we won't have DRM/Virtio GPU. >> OTOH, the dummy console really should not depend on anything, as it is >> only doing dummy things. >> >>> >>> So what about allowing CONFIG_VT on s390 only if we have PCI? >>> >>> >>> diff --git a/drivers/tty/Kconfig b/drivers/tty/Kconfig >>> index 84810075a6a0..1c7fe09d6f90 100644 >>> --- a/drivers/tty/Kconfig >>> +++ b/drivers/tty/Kconfig >>> @@ -11,7 +11,7 @@ if TTY >>> >>> config VT >>> bool "Virtual terminal" if EXPERT >>> - depends on !UML >>> + depends on !UML && (!S390 || PCI) >>> select INPUT >>> default y >>> ---help--- >>> >> >> Would cover your use case, but feels wrong to me... config dependencies >> aren't fun :/ >>