I had the same problems, I ended up using Manjaro Architect as an installer. I have a dual graphics MacBook Pro 8,2 (2011). after the installation to keep booting had to edit the grub config a bit to keep it boot. I disabled the radeon card on bootup by changing GRUB_CMDLINE_LINUX_DEFAULT in /etc/default/grub
GRUB_CMDLINE_LINUX_DEFAULT=“quiet splash i915.lvds_channel_mode=2 i915.modeset=1 i915.lvds_use_ssc=0“
In /etc/grub.d/10_linux
I changed
else
if [ "x$GRUB_GFXPAYLOAD_LINUX" != xtext ]; then
echo " load_video" | sed "s/^/$submenu_indentation/"
fi
echo " set gfxpayload=$GRUB_GFXPAYLOAD_LINUX" | sed "s/^/$submenu_indentation/"
fi
echo " insmod gzio" | sed "s/^/$submenu_indentation/"
to
else
if [ "x$GRUB_GFXPAYLOAD_LINUX" != xtext ]; then
echo " load_video" | sed "s/^/$submenu_indentation/"
fi
echo " set gfxpayload=$GRUB_GFXPAYLOAD_LINUX" | sed "s/^/$submenu_indentation/"
fi
echo " outb 0x728 1" | sed "s/^/$submenu_indentation/"
echo " outb 0x710 2" | sed "s/^/$submenu_indentation/"
echo " outb 0x740 2" | sed "s/^/$submenu_indentation/"
echo " outb 0x750 0" | sed "s/^/$submenu_indentation/"
echo " insmod gzio" | sed "s/^/$submenu_indentation/"
then updated update-grub
hope that info can help you