Writing to /dev/fb0

[Sergey Manucharian]

Excerpts from Sergey Manucharian's message from Fri 21-Jun-19 13:34:
> Excerpts from Oleksandr Tymoshenko's message from Fri 21-Jun-19 12:05:
> > You probably can convert this source file from my tslib branch to
> > standalone app:
> > 
> > https://github.com/gonzoua/tslib/blob/freebsd/tests/fbutils-bsd.c
> > 
> I added "main" and it draws a red rectangle!
> 
> int main (int argc, char** argv)
> {       
>         
>         open_framebuffer();
>         setcolor (4, 0xff0000);
>         rect(100, 200, 200, 300, 4);
>         close_framebuffer();
> }

As I already mentioned, these messages

  WARNING: Device driver fb has set "memattr" inconsistently (drv 0 pmap 3).

flood console. So, the actual performance is very poor because of that, 
thus the framebuffer is practically unusable.

The message comes from:

  sys/vm/device_pager.c

I tried to understand the purpose of the corresponding commit:

https://lists.freebsd.org/pipermail/svn-src-head/2016-May/085608.html
https://reviews.freebsd.org/D6149

However, I don't understand how to eliminate that, how to deal with the
"memattr". Disabling the message itself in "sys/vm/device_pager.c"
significantly improves the performance.

Would anybody advise please?

Thanks,
Ϟϻ