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

From: Javier Martinez Canillas <javierm@redhat.com>
To: Jani Nikula <jani.nikula@linux.intel.com>, linux-kernel@vger.kernel.org
Cc: linux-fbdev@vger.kernel.org, "David Airlie" <airlied@linux.ie>,
	"Joonas Lahtinen" <joonas.lahtinen@linux.intel.com>,
	dri-devel@lists.freedesktop.org,
	"Gurchetan Singh" <gurchetansingh@chromium.org>,
	"Gerd Hoffmann" <kraxel@redhat.com>,
	amd-gfx@lists.freedesktop.org,
	"VMware Graphics" <linux-graphics-maintainer@vmware.com>,
	"Peter Robinson" <pbrobinson@gmail.com>,
	"Neal Gompa" <ngompa13@gmail.com>,
	"Dave Airlie" <airlied@redhat.com>,
	"Chia-I Wu" <olvaffe@gmail.com>,
	"Ben Skeggs" <bskeggs@redhat.com>,
	"Michel Dänzer" <michel@daenzer.net>,
	"Maarten Lankhorst" <maarten.lankhorst@linux.intel.com>,
	"Maxime Ripard" <mripard@kernel.org>,
	"Hans de Goede" <hdegoede@redhat.com>,
	"Rodrigo Vivi" <rodrigo.vivi@intel.com>,
	nouveau@lists.freedesktop.org,
	virtualization@lists.linux-foundation.org,
	"Pekka Paalanen" <pekka.paalanen@collabora.com>,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	"Pan, Xinhui" <Xinhui.Pan@amd.com>,
	spice-devel@lists.freedesktop.org,
	"Daniel Vetter" <daniel@ffwll.ch>,
	"Alex Deucher" <alexander.deucher@amd.com>,
	intel-gfx@lists.freedesktop.org,
	"Christian König" <christian.koenig@amd.com>,
	"Zack Rusin" <zackr@vmware.com>
Subject: Re: [Nouveau] [RESEND PATCH 2/5] drm: Move nomodeset kernel parameter handler to the DRM subsystem
Date: Wed, 3 Nov 2021 14:09:05 +0100	[thread overview]
Message-ID: <33807d3c-9dd1-241a-ad23-0e0d4fba13e1@redhat.com> (raw)
In-Reply-To: <87tugtbdob.fsf@intel.com>

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