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 <xres>x<yres>[-(rgb|bgr|<bpp>)] 54 The EFI stub will search for a display mode that matches the specified 55 horizontal and vertical resolution, and optionally bit depth, and set 56 the mode of the display to it if one is found. The bit depth can either 57 "rgb" or "bgr" to match specifically those pixel formats, or a number 58 for a mode with matching bits per pixel. 59 60 auto 61 The EFI stub will choose the mode with the highest resolution (product 62 of horizontal and vertical resolution). If there are multiple modes 63 with the highest resolution, it will choose one with the highest color 64 depth. 65 66 list 67 The EFI stub will list out all the display modes that are available. A 68 specific mode can then be chosen using one of the above options for the 69 next boot. 70 71 Edgar Hucek <gimli@dark-green.com>
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