On Tue, Jan 18, 2022 at 9:10 AM Geert Uytterhoeven [off-list ref] wrote:

Hi Gerd,

On Tue, Jan 18, 2022 at 7:30 AM Gerd Hoffmann [off-list ref] wrote:

quoted

Also note that using a shadow framebuffer allows to decouple fbcon
updates and scanout framebuffer updates.  Can be used to speed up
things without depending on the 2d blitter.

Assuming accesses to the shadow frame buffer are faster than accesses
to the scanout frame buffer. While this is true on modern hardware,
this is not the case on all hardware.  Especially if the shadow frame
buffer has a higher depth (XRGB8888) than the scanout frame buffer
(e.g. Cn)...

The funny thing is that the systems we are interested in, once used
to be known for their graphics capabilities and/or performance...

That's just a pure strawman. No one is forcing you to run your shadow
buffer with xrgb8888. You can already do C8, any any other C1 is a few
lines of code. Which I can't type for you, because I don't have such
high performance hardware, but if someone would have spent hacking
instead of typing mails any time this came up the past few years, we'd
have it long ago. It's really not hard.

Same goes for modesetting support in the fbdev emulation layer (that's
a bit more work, but really not much) and really anything. And we do
actually merge additions in the emulation support pretty quickly. If
they show up.
-Daniel

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch