Reasons for keeping sc(4) and libvgl ?

From: Emmanuel Vadot <>
Date: Fri, 26 Nov 2021 15:04:54 UTC
 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.


Emmanuel Vadot <> <>