Re: Reasons for keeping sc(4) and libvgl ?

From: Stefan Blachmann <>
Date: Fri, 26 Nov 2021 15:45:17 UTC
Main technical reasons why I consider sc(4) essential:

- vt/vesa.ko break suspend/resume on nvidia cards. To make
suspend/resume work on computers with nvidia, it is necessary to build
a kernel *without* vt/vesa modules. See

- vt is so horridly buggy that it is no fun to use it at all if one is
accustomed to well-working, bugfree sc(4). Just one example:

The hate and disregard against sc(4) and against nvidia and the
arrogance that can be observed from some FreeBSD core guys amazes me
again and again.
I often wonder why Nvidia has not already dropped FreeBSD support due
to such attitudes.

On 11/26/21, Emmanuel Vadot <> wrote:
>  Hello all,
>  I'm currently re-implementing the framebuffer code in linuxkpi for
> drm-kmod and this made me look at sc(4), vt(4) and friends.
>  So I looked at what sc could do and vt couldn't and vice-versa.
>  What sc(4) can't do :
>  - Work with EFI firmware.
>  - Support UTF-8
>  - Maybe other things but everything here is EFI-based so let me know.
>  What vt(4) can't do :
>  - You can't get the modes or adapter info with vidcontrol.
>    vidcontrol -i mode is really made for anything vesa based as it
> iterates on all the modes and display them if present.
>    In the modern world (EFI), we don't have that, EFI GOP doesn't
> support changing resolution after ExitBootService was called so there
> is only one "mode". I could possibly hack some patch so vidcontrol -i
> mode/adapter would work and display the current framebuffer info if
> people wants (but I honestly doubt that vidcontrol is useful at all in
> an EFI world).
>  - "Blanking" screen doesn't do what you think it does. For some reason
> in vt(4) we just write black colors on the screen and ignore the blank
> mode passed in the ioctl.
>    Now again, blanking/dpms/blah isn't possible with efi_fb but it make
> sense to fix vt(4) and drm-kmod so it calls the drm module blanking
> function, I'll work on that next week.
>   - There is no screensaver, again see notes above for dpms but do
> people still use sc(4) just for the screensaver ??
>   - Maybe other things, please let me know.
>  For libvgl it probably made sense back in the 90s but does it now ??
>  Based on my small list I don't see any good reason to keep sc(4) but
> maybe I've missed something bigger so please let me know.
>  P.S.: I'm really not interested by people saying stuff like
>  "I've always used sc(4), it works for me don't touch it"
>  without some technical argument.
>  Cheers,
> --
> Emmanuel Vadot <> <>