Related articles * [ATI](/index.php/ATI "ATI") * [Intel graphics](/index.php/Intel_graphics "Intel graphics") * [Nouveau](/index.php/Nouveau "Nouveau") Kernel [Mode Setting](https://en.wikipedia.org/wiki/Mode-setting "wikipedia:Mode-setting") (KMS) is a method for setting display resolution and depth in the kernel space rather than user space. The Linux kernel's implementation of KMS enables native resolution in the framebuffer and allows for instant console (tty) switching. KMS also enables newer technologies (such as DRI2) which will help reduce artifacts and increase 3D performance, even kernel space power-saving. **Note:** The proprietary [NVIDIA](/index.php/NVIDIA "NVIDIA") driver (since 364.12) also implements kernel mode-setting, but it does not use the built-in kernel implementation and it lacks an fbdev driver for the high-resolution console. ## Contents * [1 Background](#Background) * [2 Installation](#Installation) * [2.1 Late KMS start](#Late_KMS_start) * [2.2 Early KMS start](#Early_KMS_start) * [3 Troubleshooting](#Troubleshooting) * [3.1 My fonts are too tiny](#My_fonts_are_too_tiny) * [3.2 Problem upon bootloading and dmesg](#Problem_upon_bootloading_and_dmesg) * [4 Forcing modes and EDID](#Forcing_modes_and_EDID) * [4.1 Forcing modes](#Forcing_modes) * [5 Disabling modesetting](#Disabling_modesetting) ## Background Previously, setting up the video card was the job of the X server. Because of this, it was not easily possible to have fancy graphics in virtual consoles. Also, each time a switch from X to a virtual console was made (`Ctrl+Alt+F1`), the server had to give control over the video card to the kernel, which was slow and caused flickering. The same "painful" process happened when the control was given back to the X server (`Ctrl+Alt+F7`). With Kernel Mode Setting (KMS), the kernel is now able to set the mode of the video card. This makes fancy graphics during bootup, virtual console and X fast switching possible, among other things. ## Installation At first, note that for *any* method you use, you should *always* disable: * Any `vga=` options in your bootloader as these will conflict with the native resolution enabled by KMS. * Any `video=` lines that enable a framebuffer that conflicts with the driver. * Any other framebuffer drivers (such as [uvesafb](/index.php/Uvesafb "Uvesafb")). ### Late KMS start [Intel](/index.php/Intel "Intel"), [Nouveau](/index.php/Nouveau "Nouveau"), [ATI](/index.php/ATI "ATI") and [AMDGPU](/index.php/AMDGPU "AMDGPU") drivers already enable KMS automatically for all chipsets, so you need not install it manually. The proprietary [NVIDIA](/index.php/NVIDIA "NVIDIA") driver supports KMS (since 364.12), which has to be [manually enabled](/index.php/NVIDIA#DRM_kernel_mode_setting "NVIDIA"). The proprietary [AMD Catalyst](/index.php/AMD_Catalyst "AMD Catalyst") driver does not support KMS. In order to use KMS you have to replace it with the open-source [ATI](/index.php/ATI "ATI") driver. ### Early KMS start **Tip:** If you encounter problems with the resolution, you can check whether [enforcing the mode](#Forcing_modes_and_EDID) helps. KMS is typically initialized after the [initramfs stage](/index.php/Arch_boot_process#initramfs "Arch boot process"). However it is possible to already enable KMS during the initramfs stage. Add the module `radeon`/`amdgpu` (for ATI/AMD cards), `i915` (for Intel integrated graphics) or `nouveau` (for Nvidia cards) to the `MODULES` line in `/etc/mkinitcpio.conf`. For example: `/etc/mkinitcpio.conf` `MODULES=(... i915 ...)` **Note:** Intel users might need to add `intel_agp` before `i915` to suppress the ACPI errors. This might be required for resuming from hibernation to work with changed display configuration! If you are using a custom EDID file (not applicable for the built-in resolutions), you should embed it into initramfs as well: `/etc/mkinitcpio.conf` `FILES=(/usr/lib/firmware/edid/your_edid.bin)` [Regenerate the initramfs](/index.php/Regenerate_the_initramfs "Regenerate the initramfs"). ## Troubleshooting ### My fonts are too tiny See [Fonts#Console fonts](/index.php/Fonts#Console_fonts "Fonts") for how to change your console font to a large font. The Terminus font ([terminus-font](https://www.archlinux.org/packages/?name=terminus-font)) is available in many sizes, such as `ter-132n` which is larger. Alternatively, [disabling modesetting](#Disabling_modesetting) might switch to lower resolution and make fonts appear larger. ### Problem upon bootloading and dmesg Polling for connected display devices on older systems can be quite expensive. Poll will happen periodically and can in worst cases take several hundred milliseconds, depending on the hardware. This will cause visible stalls, for example in video playback. These stalls might happen even when your video is on HDP output but you have other non HDP outputs in your hw configuration. If you experience stalls in display output occurring every 10 seconds, disabling polling might help. If you see an error code of `0x00000010 (2)` while booting up, (you will get about 10 lines of text, the last part denoting that error code), use: `/etc/modprobe.d/modprobe.conf` `options drm_kms_helper poll=0` ## Forcing modes and EDID If your native resolution is not automatically configured or no display at all is detected, then your monitor might send none or just a skewed [EDID](https://en.wikipedia.org/wiki/EDID "wikipedia:EDID") file. The kernel will try to catch this case and will set one of the most typical resolutions. In case you have the EDID file for your monitor you merely not to explicitly enforce it (see below). However most often one does not have direct access to sane file and it is necessary to either extract an existing one and fix it or to generate a new one. Generating new EDID binaries for various resolutions and configurations is possible during kernel compilation by following the [upstream documentation](https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/EDID/HOWTO.txt) (also see [here](https://www.osadl.org/Single-View.111+M5315d29dd12.0.html) for a short guide). Other solutions are outlined in detail this [article](https://kodi.wiki/view/Creating_and_using_edid.bin_via_xorg.conf). Extracting an existing one is in most cases easier, e.g. if your monitor works fine under Windows you might have luck extracting the EDID from the corresponding driver, or if a similar monitor works which has the same settings you may use `get-edid` from the [read-edid](https://www.archlinux.org/packages/?name=read-edid) package. After having prepared your EDID place it in a folder, e.g. called `edid` under `/usr/lib/firmware` and copy your binary into it. To load it at boot, specify the following in the [kernel command line](/index.php/Kernel_command_line "Kernel command line"): ``` drm_kms_helper.edid_firmware=edid/your_edid.bin ``` or alternatively (since kernel 4.15), one may also enforce the EDID information on a lower level, using: ``` drm.edid_firmware=edid/your_edid.bin ``` In order to apply it only to a specific monitor use: ``` drm_kms_helper.edid_firmware=VGA-1:edid/your_edid.bin ``` For the built-in resolutions, refer to the table below. The **Name** column specifies the name which one is supposed to use in order to enforce its usage. | **Resolution** | **Name** | | 800x600 | edid/800x600.bin | | 1024x768 | edid/1024x768.bin | | 1280x1024 | edid/1280x1024.bin | | 1600x1200 (kernel 3.10 or higher) | edid/1600x1200.bin | | 1680x1050 | edid/1680x1050.bin | | 1920x1080 | edid/1920x1080.bin | If you are doing early [KMS](/index.php/KMS "KMS"), you must include the custom EDID file in the [initramfs](#Early_KMS_start) otherwise you will run into problems. ### Forcing modes **Warning:** The method described below is somehow incomplete because e.g. [Xorg](/index.php/Xorg "Xorg") does not take into account the resolution specified, so users are encouraged to use the method described above. However, specifying resolution with `video=` command line may be useful in some scenarios. From [the nouveau wiki](http://nouveau.freedesktop.org/wiki/KernelModeSetting): A mode can be forced on the kernel command line. Unfortunately, the command line option video is poorly documented in the DRM case. Bits and pieces on how to use it can be found in * [http://cgit.freedesktop.org/nouveau/linux-2.6/tree/Documentation/fb/modedb.txt](http://cgit.freedesktop.org/nouveau/linux-2.6/tree/Documentation/fb/modedb.txt) * [http://cgit.freedesktop.org/nouveau/linux-2.6/tree/drivers/gpu/drm/drm_fb_helper.c](http://cgit.freedesktop.org/nouveau/linux-2.6/tree/drivers/gpu/drm/drm_fb_helper.c) The format is: ``` video=:x[M][R][-][@][i][m][eDd] ``` * ``: Connector, e.g. DVI-I-1, see `/sys/class/drm/` for available connectors * ` x `: resolution * `M`: compute a CVT mode? * `R`: reduced blanking? * `-`: color depth * `@`: refresh rate * `i`: interlaced (non-CVT mode) * `m`: margins? * `e`: output forced to on * `d`: output forced to off * `D`: digital output forced to on (e.g. DVI-I connector) You can override the modes of several outputs using `video=` several times, for instance, to force `DVI` to *1024x768* at *85 Hz* and `TV-out` off: ``` video=DVI-I-1:1024x768@85 video=TV-1:d ``` To get the name and current status of connectors, you can use the following shell oneliner: `$ for p in /sys/class/drm/*/status; do con=${p%/status}; echo -n "${con#*/card?-}: "; cat $p; done` ``` DVI-I-1: connected HDMI-A-1: disconnected VGA-1: disconnected ``` ## Disabling modesetting You may want to disable KMS for various reasons, such as getting a blank screen or a "no signal" error from the display, when using the Catalyst driver, etc. To disable KMS add `nomodeset` as a kernel parameter. See [Kernel parameters](/index.php/Kernel_parameters "Kernel parameters") for more info. Along with `nomodeset` kernel parameter, for Intel graphics card you need to add `i915.modeset=0` and for Nvidia graphics card you need to add `nouveau.modeset=0`. For Nvidia Optimus dual-graphics system, you need to add all the three kernel parameters (i.e. `"nomodeset i915.modeset=0 nouveau.modeset=0"`). **Note:** Some [Xorg](/index.php/Xorg "Xorg") drivers will not work with KMS disabled. See the wiki page on your specific driver for details.