Re: Reasons for keeping sc(4) and libvgl ?
- In reply to: Emmanuel Vadot : "Reasons for keeping sc(4) and libvgl ?"
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Date: Fri, 26 Nov 2021 19:17:00 UTC
Honourable committers, dear subscribers, W dniu 26.11.2021 o 16:04, Emmanuel Vadot pisze: > > 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, > I responded to this inquiry on IRC earlier, but will also give some feedback here. There is only one reason for me to still use sc(4) on a few amd64 machines not running X11 servers which have either old KVMs or directly connected monitors: the ability to use saver(4) with green_saver.ko which can power off the monitor via DPMS. Probably it is one of the most missing features of vt(4). Regards, -- Marek Zarychta FreeBSD user since mid-1990s