1 ==============
2 What is efifb?
3 ==============
4
5 This is a generic EFI platform driver for syst
6 system must be booted via the EFI stub for thi
7 both firmware with Graphics Output Protocol (G
8 systems with only Universal Graphics Adapter (
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
23 machine.
24
25 You have to add the following kernel parameter
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 dis
37 address, so these should work out of the box w
38
39 Accepted options:
40
41 ======= ======================================
42 nowc Don't map the framebuffer write combin
43 to workaround side-effects and slowdow
44 when large amounts of console data are
45 ======= ======================================
46
47 Options for GOP displays:
48
49 mode=n
50 The EFI stub will set the mode of the
51 possible.
52
53 <xres>x<yres>[-(rgb|bgr|<bpp>)]
54 The EFI stub will search for a display
55 horizontal and vertical resolution, an
56 the mode of the display to it if one i
57 "rgb" or "bgr" to match specifically t
58 for a mode with matching bits per pixe
59
60 auto
61 The EFI stub will choose the mode with
62 of horizontal and vertical resolution)
63 with the highest resolution, it will c
64 depth.
65
66 list
67 The EFI stub will list out all the dis
68 specific mode can then be chosen using
69 next boot.
70
71 Edgar Hucek <gimli@dark-green.com>
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