0001 ==============
0002 What is efifb?
0003 ==============
0004
0005 This is a generic EFI platform driver for systems with UEFI firmware. The
0006 system must be booted via the EFI stub for this to be usable. efifb supports
0007 both firmware with Graphics Output Protocol (GOP) displays as well as older
0008 systems with only Universal Graphics Adapter (UGA) displays.
0009
0010 Supported Hardware
0011 ==================
0012
0013 - iMac 17"/20"
0014 - Macbook
0015 - Macbook Pro 15"/17"
0016 - MacMini
0017 - ARM/ARM64/X86 systems with UEFI firmware
0018
0019 How to use it?
0020 ==============
0021
0022 For UGA displays, efifb does not have any kind of autodetection of your
0023 machine.
0024
0025 You have to add the following kernel parameters in your elilo.conf::
0026
0027 Macbook :
0028 video=efifb:macbook
0029 MacMini :
0030 video=efifb:mini
0031 Macbook Pro 15", iMac 17" :
0032 video=efifb:i17
0033 Macbook Pro 17", iMac 20" :
0034 video=efifb:i20
0035
0036 For GOP displays, efifb can autodetect the display's resolution and framebuffer
0037 address, so these should work out of the box without any special parameters.
0038
0039 Accepted options:
0040
0041 ======= ===========================================================
0042 nowc Don't map the framebuffer write combined. This can be used
0043 to workaround side-effects and slowdowns on other CPU cores
0044 when large amounts of console data are written.
0045 ======= ===========================================================
0046
0047 Options for GOP displays:
0048
0049 mode=n
0050 The EFI stub will set the mode of the display to mode number n if
0051 possible.
0052
0053 <xres>x<yres>[-(rgb|bgr|<bpp>)]
0054 The EFI stub will search for a display mode that matches the specified
0055 horizontal and vertical resolution, and optionally bit depth, and set
0056 the mode of the display to it if one is found. The bit depth can either
0057 "rgb" or "bgr" to match specifically those pixel formats, or a number
0058 for a mode with matching bits per pixel.
0059
0060 auto
0061 The EFI stub will choose the mode with the highest resolution (product
0062 of horizontal and vertical resolution). If there are multiple modes
0063 with the highest resolution, it will choose one with the highest color
0064 depth.
0065
0066 list
0067 The EFI stub will list out all the display modes that are available. A
0068 specific mode can then be chosen using one of the above options for the
0069 next boot.
0070
0071 Edgar Hucek <gimli@dark-green.com>
