eea380ad6b
VT-d may cause overfetch of the scanout PTE, both before and after the vma (depending on the scanout orientation). bspec recommends that we provide a tile-row in either directions, and suggests using 168 PTE, warning that the accesses will wrap around the ends of the GGTT. Currently, we fill the entire GGTT with scratch pages when using VT-d to always ensure there are valid entries around every vma, including scanout. However, writing every PTE is slow as on recent devices we perform 8MiB of uncached writes, incurring an extra 100ms during resume. If instead we focus on only putting guard pages around scanout, we can avoid touching the whole GGTT. To avoid having to introduce extra nodes around each scanout vma, we adjust the scanout drm_mm_node to be smaller than the allocated space, and fixup the extra PTE during dma binding. Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Tejas Upadhyay <tejaskumarx.surendrakumar.upadhyay@intel.com> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com> Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20221130235805.221010-5-andi.shyti@linux.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.