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# Uvesafb

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In contrast with other framebuffer drivers, uvesafb needs a userspace virtualizing daemon, called v86dAUR. It may seem foolish to emulate x86 code on a x86, but this is important if one wants to use the framebuffer code on other architectures (notably non-x86 ones). It was added in kernel 2.6.24 and has many more features than the standard vesafb, including:

1. Proper blanking and hardware suspension after delay
2. Support for custom resolutions as in the system BIOS.

It should support as much hardware as vesafb.

## Installation

Install the uvesafb-dkmsAUR package.

## Configuration

Remove any framebuffer-related kernel parameter from the boot loader configuration to disable the old vesafb framebuffer from loading. The following commands should return no result:

    $ grep vga /proc/cmdline
    $ grep -ir vga /etc/modprobe.d/

If you do have a `vga=` option somewhere, you will need to remove it.

### mkinitcpio hook

Add the v86d hook to HOOKS in `/etc/mkinitcpio.conf`. This allows uvesafb to take over at boot time.

    HOOKS=(base udev v86d ...)

### Define a resolution

The settings for uvesafb are defined in `/usr/lib/modprobe.d/uvesafb.conf`.

Documentation for `mode_option` can be found at [1].

To prevent your customizations being overwritten when the package is updated, copy this file to `/etc/modprobe.d/uvesafb.conf`:

    # cp /usr/lib/modprobe.d/uvesafb.conf /etc/modprobe.d/uvesafb.conf

and then make sure `/etc/mkinitcpio.conf` includes `modconf` in the `HOOKS` array.

To make changes take effect, regenerate the initramfs and reboot the system.

### Optimizing resolution

A list of possible resolutions can be generated via the following command:

    $ cat /sys/bus/platform/drivers/uvesafb/uvesafb.0/vbe_modes

Users can then modify `/usr/lib/modprobe.d/uvesafb.conf` with any entry returned above.

### Checking current resolution

Either of following commands can be used to show the current framebuffer resolution as a sanity check to see that settings are honored:

    $ cat /sys/devices/virtual/graphics/fbcon/subsystem/fb0/virtual_size

    $ cat /sys/class/graphics/fb0/virtual_size

## Kernel module parameters

If you compile your own kernel then you can also compile uvesafb into the kernel and run v86d later. In this case, the options can be passed as kernel parameters in the format `video=uvesafb:options`.

## Troubleshooting

### Uvesafb cannot reserve memory

Check if you forgot to remove any `vga=` kernel parameter − this overrides the UVESA framebuffer with a standard VESA one.

Try to add `video=vesa:off vga=normal` to the kernel command line.

## See also

- Uvesafb Kernel Page
- Gentoos uvesafb Page
- VESA mode numbers

Categories:

- Graphics
- Eye candy

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