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

On 2021-11-26 07:04, 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.
I always use sc(4). So please don't remove it.
Technical reason:
On nVidia hardware (a|g)pu's I require the following in loader.conf(5)
kern.vty=sc
if not, the EOL is always at the end of the screen width. Not at the
end of the line of text. There are other problems with the pasted text
as well.
That's my only argument against it's removal. Thanks for bringing it up. :-)

--Chris
> 
>  Cheers,