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

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Message-ID: <33807d3c-9dd1-241a-ad23-0e0d4fba13e1@redhat.com>
Date:   Wed, 3 Nov 2021 14:09:05 +0100
From:   Javier Martinez Canillas <javierm@...hat.com>
To:     Jani Nikula <jani.nikula@...ux.intel.com>,
        linux-kernel@...r.kernel.org
Cc:     Peter Robinson <pbrobinson@...il.com>,
        Michel Dänzer <michel@...nzer.net>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Pekka Paalanen <pekka.paalanen@...labora.com>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        Neal Gompa <ngompa13@...il.com>,
        Alex Deucher <alexander.deucher@....com>,
        Ben Skeggs <bskeggs@...hat.com>, Chia-I Wu <olvaffe@...il.com>,
        Christian König <christian.koenig@....com>,
        Daniel Vetter <daniel@...ll.ch>,
        Dave Airlie <airlied@...hat.com>,
        David Airlie <airlied@...ux.ie>,
        Gerd Hoffmann <kraxel@...hat.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Gurchetan Singh <gurchetansingh@...omium.org>,
        Hans de Goede <hdegoede@...hat.com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        "Pan, Xinhui" <Xinhui.Pan@....com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        VMware Graphics <linux-graphics-maintainer@...are.com>,
        Zack Rusin <zackr@...are.com>, amd-gfx@...ts.freedesktop.org,
        dri-devel@...ts.freedesktop.org, intel-gfx@...ts.freedesktop.org,
        linux-fbdev@...r.kernel.org, nouveau@...ts.freedesktop.org,
        spice-devel@...ts.freedesktop.org,
        virtualization@...ts.linux-foundation.org
Subject: Re: [RESEND PATCH 2/5] drm: Move nomodeset kernel parameter handler
 to the DRM subsystem

Hello Jani,

On 11/3/21 13:56, Jani Nikula wrote:

[snip]

>>  
>> +obj-y += drm_nomodeset.o
> 
> This is a subtle functional change. With this, you'll always have
> __setup("nomodeset", text_mode) builtin and the parameter available. And
> using nomodeset will print out the pr_warn() splat from text_mode(). But
> removing nomodeset will have no impact if CONFIG_VGA_CONSOLE=n as that
> leads to vgacon_text_force() always returning false.
>

Yes, that's what I decided at the end to make it unconditional. That
way the same behaviour is preserved (even when only DRM drivers are
using the exported symbol).
 
> To not make functional changes, this should be:
> 
> obj-$(CONFIG_VGA_CONSOLE) += drm_nomodeset.o
>

Right, that should work.

> Now, going with the cleanup in this series, maybe we should make the
> functional change, and break the connection to CONFIG_VGA_CONSOLE
> altogether, also in the header?
> 
> (Maybe we'll also need a proxy drm kconfig option to only have
> drm_modeset.o builtin when CONFIG_DRM != n.)
>

See my other email. I believe the issue is drivers/gpu/drm always
being included even when CONFIG_DRM is not set.

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