kernel-packages team mailing list archive

[Stefan Bader <stefan.bader@xxxxxxxxxxxxx>]

Odd, in theory that change should only affect the MTRR cache mode of the video memory for the generic VESA framebuffer driver. And while that is used initially it gets replaced later on by the special driver for radeon.
Maybe two things: First, after completing boot into an affected kernel, could you do a "cat /proc/mtrr" and add the output of that to this bug report.
Second, looking at the documentation it looks like it should be possible to disable that caching mode for vesafb with a kernel command-line option. If you look at /etc/default/grub, there should be a GRUB_CMDLINE_LINUX_DEFAULT (ususally it has "quiet splash" there). If you add a "video=vesafb:mtrr:0" there. Then run "sudo update-grub" and reboot. After reboot this should show up in the output of "cat /proc/cmdline" and in theory should make any "write-combining" that may have been in "cat /proc/mtrr" before go away.
Just as an additional note, looking at the dmesg output in this report, there seems to be something odd in the way the BIOS initializes MTRR. This might be the reason this specific laptop suffers from the change.

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https://bugs.launchpad.net/bugs/1561902

Title:
  Total system freeze after 3.16.0-38.52

Status in linux-lts-utopic package in Ubuntu:
  New

Bug description:
  This should have been reported already last year, but here it goes.

  Problem:
  My laptop is a ASUS N71JA and works perfectly in Windows. Everything was fine with Xubuntu 14.04 through kernels 3.13 and 3.16 up to 3.16.0-38.52. Desktop freezes, like totally dies with hard power reset being the only option, every now and then from this kernel and onwards. This affects 3.19 and 4.2.0 kernels released after this date as well. No Magic SysRq possible and I can't see anything fancy in syslog or kern.log. Desktop can die anytime between immediately after boot or after a few hours, but it happens completely randomly and is hard to debug.

  Workaround:
  3.16.0-38.52 was released in May 2015 (https://bugs.launchpad.net/ubuntu/+source/linux-lts-utopic/+bug/1452882).
  3.16.0-37.51 and 3.16.0-36.48 have NEVER frozen. 

  The only non-upstream change that was made to 3.16.0-38.52 was
  "vesafb: Set mtrr:3 (write-combining) as default"
  (https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1434581). This
  is probably not implemented in the mainline kernel tree, right? I've
  been using mainline 3.16.7-ckt24-trusty without any problems now for
  over a month (http://kernel.ubuntu.com/~kernel-
  ppa/mainline/v3.16.7-ckt24-trusty/) i.e. it seems like 1434581 is
  causing the problem.

  Can this be verified by some other method e.g. by disabling/reverting
  1434581 in a "normal" non-mainline kernel?

  Solution:
  ?
  --- 
  ApportVersion: 2.14.1-0ubuntu3.19
  Architecture: amd64
  AudioDevicesInUse:
   USER        PID ACCESS COMMAND
   /dev/snd/controlC2:  isak       1669 F.... pulseaudio
   /dev/snd/controlC0:  isak       1669 F.... pulseaudio
   /dev/snd/controlC1:  isak       1669 F.... pulseaudio
  CurrentDesktop: XFCE
  DistroRelease: Ubuntu 14.04
  HibernationDevice: RESUME=UUID=188824e0-028f-4004-92b9-9e627eff4d5c
  MachineType: ASUSTeK Computer Inc. N71Ja
  Package: linux (not installed)
  ProcFB: 0 radeondrmfb
  ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.16.0-38-generic root=UUID=1d243640-e961-4ee3-b6d9-8e4ee5816090 ro quiet splash
  ProcVersionSignature: Ubuntu 3.16.0-38.52~14.04.1-generic 3.16.7-ckt10
  RelatedPackageVersions:
   linux-restricted-modules-3.16.0-38-generic N/A
   linux-backports-modules-3.16.0-38-generic  N/A
   linux-firmware                             1.127.20
  Tags:  trusty
  Uname: Linux 3.16.0-38-generic x86_64
  UpgradeStatus: No upgrade log present (probably fresh install)
  UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo vboxusers
  _MarkForUpload: True
  dmi.bios.date: 05/14/2010
  dmi.bios.vendor: American Megatrends Inc.
  dmi.bios.version: N71Ja.206
  dmi.board.asset.tag: ATN12345678901234567
  dmi.board.name: N71Ja
  dmi.board.vendor: ASUSTeK Computer Inc.
  dmi.board.version: 1.0
  dmi.chassis.asset.tag: No Asset Tag
  dmi.chassis.type: 10
  dmi.chassis.vendor: ASUSTeK Computer Inc.
  dmi.chassis.version: 1.0
  dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrN71Ja.206:bd05/14/2010:svnASUSTeKComputerInc.:pnN71Ja:pvr1.0:rvnASUSTeKComputerInc.:rnN71Ja:rvr1.0:cvnASUSTeKComputerInc.:ct10:cvr1.0:
  dmi.product.name: N71Ja
  dmi.product.version: 1.0
  dmi.sys.vendor: ASUSTeK Computer Inc.

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