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Date:   Wed, 28 Apr 2021 11:08:21 +0200
From:   Cornelia Huck <cohuck@redhat.com>
To:     Christian Borntraeger <borntraeger@de.ibm.com>
Cc:     Thomas Huth <thuth@redhat.com>, linux-s390@vger.kernel.org,
        Heiko Carstens <hca@linux.ibm.com>,
        linux-kernel@vger.kernel.org, Vasily Gorbik <gor@linux.ibm.com>,
        Marc Hartmayer <mhartmay@linux.ibm.com>,
        Halil Pasic <pasic@linux.ibm.com>
Subject: Re: [PATCH] arch/s390/configs: Change CONFIG_VIRTIO_CONSOLE to "m"
Message-ID: <20210428110821.70aa5774.cohuck@redhat.com>
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References: <20210428082442.321327-1-thuth@redhat.com>
        <c015ef3f-ff88-113b-a089-e2af9202399a@de.ibm.com>
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On Wed, 28 Apr 2021 10:31:54 +0200
Christian Borntraeger <borntraeger@de.ibm.com> wrote:

> On 28.04.21 10:24, Thomas Huth wrote:
> > In former times, the virtio-console code had to be compiled into
> > the kernel since the old guest virtio transport had some hard de-
> > pendencies. But since the old virtio transport has been removed in
> > commit 7fb2b2d51244 ("s390/virtio: remove the old KVM virtio transport"),
> > we do not have this limitation anymore.
> > Commit bb533ec8bacd ("s390/config: do not select VIRTIO_CONSOLE via
> > Kconfig") then also lifted the hard setting in the Kconfig system, so
> > we can finally switch the CONFIG_VIRTIO_CONSOLE knob to compile this
> > driver as a module now, making it more flexible for the user to only
> > load it if it is really required.  
> 
> Isnt that a distro specific decision? I would be perfectly fine to have
> this change in Fedora, Redhat and co. Not so sure about defconfig.
> We often use the defconfig in our CI and development things to have a
> kernel config that boots up fine, even without a ramdisk. I agree that
> virtio console is no longer really the most important console but does
> it really hurt? Is any distro using the defconfig unmodified?

Having a value in the defconfig that will be sensible for most users
sounds good to me, independent of what different distros choose to do.
(Or am I misunderstanding the purpose of the defconfig?)

For booting without a ramdisk, I see that virtio-blk and virtio-input
are y, while other virtio drivers are m. That should be sufficient,
shouldn't it?