Bug#807598: [SOLVED] xserver-xorg-video-intel: [i915] No hardware acceleration

[Gilles Sadowski <gilles.sadowski@ulb.ac.be>]

Hi.

Among the boot messages, there were the following lines:
---CUT---
 [drm] This hardware requires preliminary hardware support
 See CONFIG_DRM_I915_PRELIMINARY_HW_SUPPORT, and/or modparam preliminary_hw_support
---CUT---

Then, a web search easily revealed this page:
  http://www.phoronix.com/scan.php?page=news_item&px=intel-skl-prelim-support

The workaround is to append the following to the kernel command-line:
  i915.preliminary_hw_support=1
  
Hence I modified the variables
  GRUB_CMDLINE_LINUX_DEFAULT
and
  GRUB_CMDLINE_LINUX
in
  /etc/default/grub
and then ran "update-grub".
After rebooting, DRM is working.

Perhaps this unexpected behaviour can be dealt with (or warned about) during
install...

Best regards,
Gilles