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