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

Hi Thomas,

On Wed, Jun 7, 2023 at 5:15 PM Thomas Zimmermann [off-list ref] wrote:

Am 07.06.23 um 10:48 schrieb Geert Uytterhoeven:

quoted

On Mon, Jun 5, 2023 at 4:48 PM Thomas Zimmermann [off-list ref] wrote:

quoted

--- 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.

quoted

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