42172b551c
Intel hardware allows some preemption settings to be controlled either by the kernel-mode driver exclusively, or placed under control of the user-mode drivers; on Linux we always select the userspace control option. The various registers involved in this are not documented very clearly; let's add some clarifying comments to help explain how this all works and provide some history on why our Linux drivers take the approach they do (which I believe differs from the path taken by certain other operating systems' drivers). While we're at it, let's also remove the graphics version 12 upper bound on this programming. As described, we don't have any plans to move away from UMD control of preemption settings on future platforms, and there's currently no reason to believe that the hardware will fundamentally change how these registers and settings work after version 12. Bspec: 45921, 45858, 45863 Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Lionel Landwerlin <lionel.g.landwerlin@intel.com> Suggested-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Signed-off-by: Matt Roper <matthew.d.roper@intel.com> Reviewed-by: Wayne Boyer <wayne.boyer@intel.com> Acked-by: Tapani Pälli <tapani.palli@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20220907212410.22623-1-matthew.d.roper@intel.com
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.