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14c574f35c
Add video=efifb:list option to list the modes that are available. Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> Link: https://lore.kernel.org/r/20200518190716.751506-20-nivedita@alum.mit.edu Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
72 lines
2.2 KiB
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72 lines
2.2 KiB
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==============
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What is efifb?
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==============
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This is a generic EFI platform driver for systems with UEFI firmware. The
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system must be booted via the EFI stub for this to be usable. efifb supports
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both firmware with Graphics Output Protocol (GOP) displays as well as older
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systems with only Universal Graphics Adapter (UGA) displays.
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Supported Hardware
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==================
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- iMac 17"/20"
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- Macbook
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- Macbook Pro 15"/17"
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- MacMini
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- ARM/ARM64/X86 systems with UEFI firmware
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How to use it?
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==============
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For UGA displays, efifb does not have any kind of autodetection of your
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machine.
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You have to add the following kernel parameters in your elilo.conf::
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Macbook :
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video=efifb:macbook
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MacMini :
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video=efifb:mini
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Macbook Pro 15", iMac 17" :
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video=efifb:i17
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Macbook Pro 17", iMac 20" :
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video=efifb:i20
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For GOP displays, efifb can autodetect the display's resolution and framebuffer
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address, so these should work out of the box without any special parameters.
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Accepted options:
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======= ===========================================================
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nowc Don't map the framebuffer write combined. This can be used
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to workaround side-effects and slowdowns on other CPU cores
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when large amounts of console data are written.
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======= ===========================================================
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Options for GOP displays:
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mode=n
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The EFI stub will set the mode of the display to mode number n if
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possible.
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<xres>x<yres>[-(rgb|bgr|<bpp>)]
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The EFI stub will search for a display mode that matches the specified
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horizontal and vertical resolution, and optionally bit depth, and set
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the mode of the display to it if one is found. The bit depth can either
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"rgb" or "bgr" to match specifically those pixel formats, or a number
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for a mode with matching bits per pixel.
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auto
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The EFI stub will choose the mode with the highest resolution (product
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of horizontal and vertical resolution). If there are multiple modes
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with the highest resolution, it will choose one with the highest color
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depth.
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list
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The EFI stub will list out all the display modes that are available. A
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specific mode can then be chosen using one of the above options for the
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next boot.
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Edgar Hucek <gimli@dark-green.com>
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