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

W dniu 21.06.2022 o 20:19, Emmanuel Vadot pisze:
>   Hello,
>
> On Fri, 26 Nov 2021 16:04:54 +0100
> Emmanuel Vadot <manu@bidouilliste.com> 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 <manu@bidouilliste.com> <manu@freebsd.org>
>>
>   I've put up in phab removing sc(4) from GENERIC and MINIMAL :
>
>   https://reviews.freebsd.org/D35538
>   https://reviews.freebsd.org/D35539
>
>   If you have any good reason that sc(4) should be included in those
> kernel config for amd64 (no other arches was touched) please provide
> some argument on the reviews.
>
>   Cheers,
>
Thanks for heads up. Unfortunately, it will be a great loss. The waste 
of power resources might increase since vt(4) still doesn't support VESA 
Display Power Management Signaling which some of the servers are heavily 
relying on. It's a step backward in terms of green computing and amidst 
the power crisis, we are heading in Europe.

-- 
Marek Zarychta