Documentation/fb/efifb.rst

   1 ==============
   2 What is efifb?
   3 ==============
   4
   5 This is a generic EFI platform driver for systems with UEFI firmware. The
   6 system must be booted via the EFI stub for this to be usable. efifb supports
   7 both firmware with Graphics Output Protocol (GOP) displays as well as older
   8 systems with only Universal Graphics Adapter (UGA) displays.
   9
  10 Supported Hardware
  11 ==================
  12
  13 - iMac 17"/20"
  14 - Macbook
  15 - Macbook Pro 15"/17"
  16 - MacMini
  17 - ARM/ARM64/X86 systems with UEFI firmware
  18
  19 How to use it?
  20 ==============
  21
  22 For UGA displays, efifb does not have any kind of autodetection of your
  23 machine.
  24
  25 You have to add the following kernel parameters in your elilo.conf::
  26
  27         Macbook :
  28                 video=efifb:macbook
  29         MacMini :
  30                 video=efifb:mini
  31         Macbook Pro 15", iMac 17" :
  32                 video=efifb:i17
  33         Macbook Pro 17", iMac 20" :
  34                 video=efifb:i20
  35
  36 For GOP displays, efifb can autodetect the display's resolution and framebuffer
  37 address, so these should work out of the box without any special parameters.
  38
  39 Accepted options:
  40
  41 ======= ===========================================================
  42 nowc    Don't map the framebuffer write combined. This can be used
  43         to workaround side-effects and slowdowns on other CPU cores
  44         when large amounts of console data are written.
  45 ======= ===========================================================
  46
  47 Options for GOP displays:
  48
  49 mode=n
  50         The EFI stub will set the mode of the display to mode number n if
  51         possible.
  52
  53 Edgar Hucek <gimli@dark-green.com>