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1==============2What is efifb?3==============4 5This is a generic EFI platform driver for systems with UEFI firmware. The6system must be booted via the EFI stub for this to be usable. efifb supports7both firmware with Graphics Output Protocol (GOP) displays as well as older8systems with only Universal Graphics Adapter (UGA) displays.9 10Supported Hardware11==================12 13- iMac 17"/20"14- Macbook15- Macbook Pro 15"/17"16- MacMini17- ARM/ARM64/X86 systems with UEFI firmware18 19How to use it?20==============21 22For UGA displays, efifb does not have any kind of autodetection of your23machine.24 25You have to add the following kernel parameters in your elilo.conf::26 27 Macbook :28 video=efifb:macbook29 MacMini :30 video=efifb:mini31 Macbook Pro 15", iMac 17" :32 video=efifb:i1733 Macbook Pro 17", iMac 20" :34 video=efifb:i2035 36For GOP displays, efifb can autodetect the display's resolution and framebuffer37address, so these should work out of the box without any special parameters.38 39Accepted options:40 41======= ===========================================================42nowc Don't map the framebuffer write combined. This can be used43 to workaround side-effects and slowdowns on other CPU cores44 when large amounts of console data are written.45======= ===========================================================46 47Options for GOP displays:48 49mode=n50 The EFI stub will set the mode of the display to mode number n if51 possible.52 53<xres>x<yres>[-(rgb|bgr|<bpp>)]54 The EFI stub will search for a display mode that matches the specified55 horizontal and vertical resolution, and optionally bit depth, and set56 the mode of the display to it if one is found. The bit depth can either57 "rgb" or "bgr" to match specifically those pixel formats, or a number58 for a mode with matching bits per pixel.59 60auto61 The EFI stub will choose the mode with the highest resolution (product62 of horizontal and vertical resolution). If there are multiple modes63 with the highest resolution, it will choose one with the highest color64 depth.65 66list67 The EFI stub will list out all the display modes that are available. A68 specific mode can then be chosen using one of the above options for the69 next boot.70 71Edgar Hucek <gimli@dark-green.com>72