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Subject: Re: [PATCH] s390/console: enable dummy console for vt
To:     Geert Uytterhoeven <geert@linux-m68k.org>,
        Christian Borntraeger <borntraeger@de.ibm.com>
Cc:     Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
        Farhan Ali <alifm@linux.vnet.ibm.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux Fbdev development list <linux-fbdev@vger.kernel.org>,
        linux-s390 <linux-s390@vger.kernel.org>,
        Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>,
        Tomi Valkeinen <tomi.valkeinen@ti.com>,
        Martin Schwidefsky <schwidefsky@de.ibm.com>,
        DRI Development <dri-devel@lists.freedesktop.org>,
        Chen Liqin <liqin.linux@gmail.com>,
        Lennox Wu <lennox.wu@gmail.com>, Jeff Dike <jdike@addtoit.com>,
        Richard Weinberger <richard@nod.at>,
        uml-devel <user-mode-linux-devel@lists.sourceforge.net>
References: <2324e2cc-ff55-4d57-2807-c7f72f9ea0ca@de.ibm.com>
 <20180215111423.96598-1-borntraeger@de.ibm.com>
 <CAMuHMdWCK1V3PWXHMNZUmFVMCSqi5xhs72mT_M=gE96TSzMN9w@mail.gmail.com>
From:   Thomas Huth <thuth@redhat.com>
Message-ID: <f621e016-3811-b9c5-e044-779adc6b420c@redhat.com>
Date:   Thu, 15 Feb 2018 12:57:37 +0100
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On 15.02.2018 12:26, Geert Uytterhoeven wrote:
> Hi Christian,
> 
> On Thu, Feb 15, 2018 at 12:14 PM, Christian Borntraeger
> <borntraeger@de.ibm.com> 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 <borntraeger@de.ibm.com>
>> ---
>> 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 think I agree with Geert - let's better fix this in a proper way
instead of doing hacks like this. I guess there will be other
architectures in the future that might want to use the dummy console
without CONFIG_IOMEM, so fixing this in drivers/video/ instead sounds
better to me.

 Thomas