On 24/08/14 17:22, [email protected] wrote: > This post has been prompted by the "Computer issues with Linux" thread, It > appear to me that some are unsure how linux works in this area these days. > This explanation is what one may call a generic approach to what the Xorg > graphics developers are aiming for, although most current open source > drivers do work this way. > > The driver for each card/family of cards is made up of three separate > drivers. First is the actual kernel part of the driver this is call KMS > (Kernel Mode Switching), the second part is the standard xorg video driver. > The third part is the mesa dri (3D) driver. Now on most modern cards the > standard xorg and the dri driver are linked to some degree. THis is because > the default xorg architecture expects the card to have a separate 2D and 3D > controlers, where as most current cards only use a single 3D graphics > (__VERY__ complex) engine. > > The kernel KMS driver has all the intertface specfic to the set up of a > particular card and this driver does all the setup of the card. Often this > driver requires access to a binary blob that contains the basic commands > for the cards engine. This driver is usually specfic to a particular card > > THe other two drivers are generally made for a "family of cards". Note this > was a major reason for the spitting off of the KMS driver as with the setup > of the card extracted to the kernel, it left the developers a __far__ > easier task to actual do the graphics programming as at this level the > programming interface does not usually change much as card design moves > forward. > > On start up __if__ KMS is enabled the kernel __will__ try and setup the > card and the console will switch to a graphics mode, most modern > distributions including debian are set up this way. It is possible to stop > the KMS being setup, unfortunately exactly where this resides in the system > has slipped my mind. > > Hmmmm, stop press........ > For the radeon open source driver this is controled (in debian) by the file > /etc/modprobe.d/radeon-kms.conf > If this is set up as "options radeon modeset=1" it will cause the kernel to > activate the apropriate KMS driver in the kernel. > > > Hope this explanation is clear..... > Lindsay
Hence therefore the reason that a change in kernel may affect the properties of KMS wrt. some graphics engines..... .btw stopping KMS via the "options radeon modeset=0" stanza worked with my 9250se on a debian squeeze system, but failed to work on a similarly dated Linux Mint installation, go figure... Robert _______________________________________________ luv-main mailing list [email protected] http://lists.luv.asn.au/listinfo/luv-main
