Re: [PATCH 30/30] fbdev: Make support for userspace interfaces configurable

Geert Uytterhoeven
2023-06-07T15:24:23Z

Hi Thomas,

On Wed, Jun 7, 2023 at 5:15 PM Thomas Zimmermann <tzimmermann@suse.de> wrote:
> Am 07.06.23 um 10:48 schrieb Geert Uytterhoeven:
> > On Mon, Jun 5, 2023 at 4:48 PM Thomas Zimmermann <tzimmermann@suse.de> wrote:
> >> --- a/drivers/video/fbdev/Kconfig
> >> +++ b/drivers/video/fbdev/Kconfig
> >> @@ -57,6 +57,15 @@ config FIRMWARE_EDID
> >> combination with certain motherboards and monitors are known to
> >> suffer from this problem.
> >>
> >> +config FB_DEVICE
> >> + bool "Provide legacy /dev/fb* device"
> >
> > Perhaps "default y if !DRM", although that does not help for a
> > mixed drm/fbdev kernel build?
>
> We could simply set it to "default y". But OTOH is it worth making it a
> default? Distributions will set it to the value they need/want. The very
> few people that build their own kernels to get certain fbdev drivers
> will certainly be able to enable the option by hand as well.

Defaulting to "n" (the default) means causing regressions when these
few people use an existing defconfig.

> > Or reserve "FB" for real fbdev drivers, and introduce a new FB_CORE,
> > to be selected by both FB and DRM_FBDEV_EMULATION?
> > Then FB_DEVICE can depend on FB_CORE, and default to y if FB.
>
> That wouldn't work. In Tumbleweed, we still have efifb and vesafb
> enabled under certain conditions; merely for the kernel console. We'd
> have to enable CONFIG_FB, which would bring back the device.

"Default y" does not mean that you cannot disable FB_DEVICE, so
you are not forced to bring back the device?

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds