I forgot to mention that when I remove the conditional loading of fbcon module and rebuild my initramfs with 'sudo update-initramfs -u', my framebuffer console works again and the device /dev/fb0 is actually created (with vga=791 in GRUB options). But it's probably a dirty hack... May be this should be done in the /usr/share/initramfs-tools/init-top/framebuffer script.
I forgot to mention that when I remove the conditional loading of fbcon module and rebuild my initramfs with 'sudo update-initramfs -u', my framebuffer console works again and the device /dev/fb0 is actually created (with vga=791 in GRUB options). But it's probably a dirty hack... May be this should be done in the /usr/share/ initramfs- tools/init- top/framebuffer script.