linux-kernel - Re: [PATCH 2/5] drm: Move nomodeset kernel parameter handler to the DRM subsystem

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Message-ID: <6bd3ff4c-c2df-5cc8-bdc5-22bc37c0cb9e@redhat.com>
Date:   Wed, 3 Nov 2021 12:21:04 +0100
From:   Javier Martinez Canillas <javierm@...hat.com>
To:     Neal Gompa <ngompa13@...il.com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Pekka Paalanen <pekka.paalanen@...labora.com>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Peter Robinson <pbrobinson@...il.com>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        Michel Dänzer <michel@...nzer.net>
Subject: Re: [PATCH 2/5] drm: Move nomodeset kernel parameter handler to the
 DRM subsystem

Hello Neal,

On 11/3/21 12:05, Neal Gompa wrote:
> On Wed, Nov 3, 2021 at 6:48 AM Javier Martinez Canillas
> <javierm@...hat.com> wrote:
>>
>> The "nomodeset" kernel cmdline parameter is handled by the vgacon driver
>> but the exported vgacon_text_force() symbol is only used by DRM drivers.
>>
>> It makes much more sense for the parameter logic to be in the subsystem
>> of the drivers that are making use of it. Let's move that to DRM.
>>
>> Suggested-by: Daniel Vetter <daniel.vetter@...ll.ch>
>> Signed-off-by: Javier Martinez Canillas <javierm@...hat.com>
>> ---
> 
> Please no, I'd much rather have a better, more meaningful option
> instead of "nomodeset". If anything, I would like this option to
> eventually do nothing and replace it with a better named option that's
> namespaced by drm on the command-line. That was part of the feedback I
> gave in the original patch set, and I still stand by that.
> 

I do agree with you that a more meaningful parameter would be desirable.

But I think that's orthogonal to this series and something that could be
done as a follow-up. That is, nomodeset isn't going away anytime soon as
that's what users are get to.

This doesn't mean that a drm.disable_native_drivers, drm.safe_mode or
whatever could be added. Internally it would also toggle the same value
but it will be much more clear to users what's the expected behaviour.

By having a module parameter under the drm namespace, it would also allow
to change this from user-space through a sysfs entry. Something that's not
currently possible for the "nomodeset" paramter.

Best regards,
-- 
Javier Martinez Canillas
Linux Engineering
Red Hat