This used to work. Last time I checked was under kernel 5.4.x. I just checked it again, tonight and it does not seem to actually direct any graphic output to /dev/fb1.
I have a 3.5" spi tft touch screen. I put a "fbcon=map:10" in the /boot/cmdline.txt and put
$this->bbcode_second_pass_code('', '# PItft 3.5" screen
dtparam=spi=on
dtoverlay=pitft35-resistive,rotate=90,speed=32000000,fps=20')
into /boot/config.txt and when it boots, I get a console. If I set up fbturbo with a config:
$this->bbcode_second_pass_code('', 'Section "Device"
Identifier "Allwinner A10/A13 FBDEV"
Driver "fbturbo"
Option "fbdev" "/dev/fb1"
Option "SwapbuffersWait" "true"
EndSection')
and start X, it displays on the HDMI (/dev/fd0?). If I change it to /dev/fb0, it still goes to the HDMI. It is as if xorg is ignoring my directive to /dev/fb1. When I do have this set and start X, the console does go numb and I cannot type anything on the cli but no graphic X window is ever displayed. I have tried using the regular fbdev driver as well and get the same result. Is there some cmdline.txt directive that needs to be put in to enable this?