Bug#569314: Enabling CONFIG_VT_HW_CONSOLE_BINDING fixed this

[Kan-Ru Chen <kanru@kanru.info>]

I think it's due to grub-pc was trying to preserve efifb. I don't know
when this was introduced.

/etc/grub.d/10_linux:64:

      # Use ELILO's generic "efifb" when it's known to be available.
      # FIXME: We need an interface to select vesafb in case efifb can't be used.
      if grep -qx "CONFIG_FB_EFI=y" /boot/config-${version} 2> /dev/null ; then
        cat << EOF
            set gfxpayload=keep
    EOF
 

> Xavi Drudis Ferran wrote:
> Is there away to tell the kernel to never activate efifb or vesafb and
> load i915 form initrd instead ? Or is there a way to unbind it from
> all outputs before loading inteldrmfb ? I'd prefer to use debian
> kernels than rebuild them at each upgrade. And I guess that compiling
> in all framebuffers in a distribution kernel is a little contrary to
> the idea of initrd, keeping the kernel small and all that.

Actually the fb subsystem was trying to unbind efifb but failed because
the stock kernel was built without CONFIG_VT_HW_CONSOLE_BINDING.

    config VT_HW_CONSOLE_BINDING
           bool "Support for binding and unbinding console drivers"
           depends on HW_CONSOLE
           default n
           ---help---
             The virtual terminal is the device that interacts with the physical
             terminal through console drivers. On these systems, at least one
             console driver is loaded. In other configurations, additional console
             drivers may be enabled, such as the framebuffer console. If more than
             1 console driver is enabled, setting this to 'y' will allow you to
             select the console driver that will serve as the backend for the
             virtual terminals.
     
             See <file:Documentation/console/console.txt> for more
             information. For framebuffer console users, please refer to
             <file:Documentation/fb/fbcon.txt>.

After enabling this, efifb can be successfully unbind and inteldrmfb is
used.

    [    0.942688] fb0: EFI VGA frame buffer device
    [   22.596877] fb: conflicting fb hw usage inteldrmfb vs EFI VGA - removing generic driver
    [   22.597101] fb0: inteldrmfb frame buffer device

-- 
Kan-Ru Chen | http://kanru.info

Q: Why are my replies five sentences or less?
A: http://five.sentenc.es/