Mode-setting is setting up the screen resolution and depth mode for the graphics card. Modern mode setting software support multiple monitors ("multi-head") and hot plugging.
Location
Mode-setting can be done in kernel space (Kernel Mode-Setting, KMS) or in user space (User-space Mode Setting, UMS). Doing mode-setting in kernel-space is more flexible and allows displaying of an error in the case of a fatal error in the kernel, even when using a user-space display server. User-space mode-setting would have needed superuser privileges for direct hardware access, so kernel-based mode-setting increases security because the user-space graphics server does not need superuser privileges. Big text
Implementations
FreeBSD
The FreeBSD Foundation has announced it is funding a FreeBSD developer to implement support for both Graphics Execution Manager (GEM) and kernel-based mode-setting.[1]
Linux
The Linux kernel got the prerequisite for kernel-based mode-setting by accepting GEM in version 2.6.28,[2] released December 2008. This will be replaced by a TTM (Translation Table Maps) memory manager which supports the GEM API.[3] TTM was developed for the ATI Radeon driver and VIA S3 Graphics chipsets.[4]
Support for Intel GMA graphic cards has been accepted in version 2.6.29 which was released on March 23, 2009.[5]
Support for pre-R600 ATI Radeon graphics cards has been accepted in version 2.6.31 which was released on September 9, 2009.[6] Support for R600 and R700 was in development within DRM and has been merged in version 2.6.32.[7] Support for Evergreen (R800) has been merged in version 2.6.34.
As NVIDIA did not release all the needed documentation for its graphics chip, the development is under the nouveau project which uses reverse engineering to get it to work. Nouveau has been accepted in version 2.6.33 of the kernel which was released on December 10, 2009. This will allow to use kernel-based mode-setting for NVIDIA cards with this driver.
Microsoft Windows
Microsoft Windows versions that are NT-based use kernel mode setting. The kernel error display made possible by kernel mode setting is known as the Blue Screen of Death.
OpenBSD
OpenBSD which has a strong focus on security is interested in getting kernel-based mode-setting in order to run X without superuser privileges.[8]
OpenSolaris
OpenSolaris will feature kernel-based mode-setting.[9] OpenSolaris also has GEM support as of snv_130.
See also
References
- ^ "GEM, KMS, and DRI Support for Intel Drivers". FreeBSD Foundation. 17 February 2011.
- ^ http://kernelnewbies.org/Linux_2_6_28#head-b957b19f6139b6bbbfabaf790bf643b1746985d6
- ^ http://www.phoronix.com/scan.php?page=news_item&px=NjY3Ng
- ^ http://www.phoronix.com/scan.php?page=news_item&px=NzMxOA
- ^ http://kernelnewbies.org/Linux_2_6_29#head-e1bab8dc862e3b477cc38d87e8ddc779a66509d1
- ^ http://kernelnewbies.org/Linux_2_6_31#head-78158343fc06e5e289f2ccaf51d6a30090a46524
- ^ http://www.phoronix.com/scan.php?page=article&item=amd_r600_r700_2d
- ^ http://www.phoronix.com/scan.php?page=news_item&px=NzA5Mg
- ^ http://www.phoronix.com/scan.php?page=news_item&px=NzIwMA
External links
- http://www.x.org/wiki/ModeSetting
- http://www.x.org/wiki/IntelGraphicsDriver – Intel driver
- http://www.x.org/wiki/RadeonFeature – ATI Radeon driver
- http://nouveau.freedesktop.org/wiki/ – NVIDIA driver (nouveau)
- http://fedoraproject.org/wiki/Features/KernelModesetting