Fashion setting

from Wikipedia, the free encyclopedia

Under mode setting is meant to set the screen resolution , refresh rate and color depth of the graphics card through software . In addition to hot-plugging , modern mode setting software also supports the use of multiple monitors (so-called multi-head operation).

Variants of the fashion setting

The mode setting can take place in the kernel space as well as in the user space.

Mode setting in user space

Under Linux and BSD , the X Window System takes care of this part, that is, the mode setting happens in user space. Before the X server is started, the graphics card is usually operated in text mode, which is normally set using the kernel parameter "vga". If the operating system reaches a certain run level (mostly 5, but with Debian, for example, 3), the X server is started.

advantages

  • Setting the graphics card to text mode is much easier to accomplish; this increases the chances of success (especially after replacing the graphics card and / or monitor, if the new hardware requires different parameters). If the graphical server no longer starts or the screen remains black (e.g. because the wrong resolution or wrong refresh rate is set), you can still use text mode, for example to import the required drivers or to change the configuration files. The operating system usually offers a “recovery mode” in which the graphical server is not started in order to carry out these tasks.

disadvantage

  • Switching from the text mode, which was set when the kernel was started, to the graphics mode leads to the fact that no picture is displayed for a short time on many monitors. Noise can also occur with tube monitors. This happens both when the operating system is started, when the graphical server is started for the first time, as well as when the graphical server has been closed or a new graphical server is started on another virtual terminal and switched to this (e.g. during the course fast user switching). Likewise, the graphical server is normally terminated and switched back to text mode when it is shut down.
  • Direct hardware access by software in user space requires extended rights, which is undesirable from a security point of view.

Mode setting in the kernel space

Linux kernel components DRM and KMS : while DRM manages the memory and the GPU, the KMS manages the display controller and is also responsible for the mode setting .

With the kernel mode setting, as is the case with the Linux kernel from version 2.6.28 for some graphics card models, the kernel already takes over the setting of the graphics card.

advantages

  • Faster switching between several graphical servers running at the same time (for example in the course of fast user switching), as no mode setting takes place if both sessions use the same parameters.
  • No flickering of the monitor when switching between several graphic servers.

Individual evidence

  1. ↑ Kernel parameters. ( Memento of the original from September 23, 2005 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. On: linux.no (engl.) @1@ 2Template: Webachiv / IABot / lxr.linux.no
  2. ↑ Kernel mode setting and memory management. On: fedoraproject.org (engl.)
  3. ↑ Kernel-Log: What 2.6.28 brings (4) - Improvements in the graphics support. On: heise.de , October 24, 2008.