Difference between revisions of "Linux-ck"

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[[Category:Kernel]]
 
[[Category:Kernel]]
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[[ja:Linux-ck]]
 
[[ru:Linux-ck]]
 
[[ru:Linux-ck]]
[[zh-CN:Linux-ck]]
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[[zh-hans:Linux-ck]]
{{Article summary start}}
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{{Related articles start}}
{{Article summary text|
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{{Related|Repo-ck}}
'''Linux-ck and headers'''
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{{Related|Modprobed-db}}
*Current version: '''3.11.1-2'''
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{{Related articles end}}
*BFS CPU scheduler: v0.441
 
*CK Patchset: 3.11-ck1
 
*Release date: 16-Sep-2013}}
 
  
{{Article summary heading|Related}}
+
== General package details ==
{{Article summary wiki|Linux-ck/Changelog}} - Linux-ck Changelog.
 
{{Article summary wiki|Repo-ck}} - Setup and contents of unofficial repo-ck.
 
{{Article summary wiki|Modprobed_db}} - Util to keep track of all probed modules.
 
{{Article summary end}}
 
  
==General Package Details==
+
{{AUR|Linux-ck}} is a package available both in [[AUR]] and in the [[#Use pre-compiled packages|unofficial repo-ck repository]] that allows users to run a kernel and headers setup patched with Con Kolivas' ck patchset[http://users.tpg.com.au/ckolivas/kernel/], including MuQSS (Multiple Queue Skiplist Scheduler, pronounced ''mux'') which replaces Brain Fuck Scheduler (BFS), his previous work. Many Arch Linux users choose this kernel for its excellent desktop interactivity and responsiveness under any load situation.
{{AUR|Linux-ck}} is a package available in the [[AUR]] and in the [[#2._Use_Pre-Compiled_Packages|unofficial linux-ck repo]] that allows users to run a kernel/headers setup patched with Con Kolivas' ck1 patchset, including the Brain Fuck Scheduler (BFS). Many Archers elect to use this package for the BFS' excellent desktop interactivity and responsiveness under any load situation.  Additionally, the bfs imparts performance gains beyond interactivity.  For example, see: [[http://repo-ck.com/bench/cpu_schedulers_compared.pdf CPU_Schedulers_Compared.pdf]].
 
  
=== Release Cycle ===
+
Ck patchset is designed for desktop/laptop use but not for servers. It provides low latency environment and works well for 16 CPUs or fewer.
Linux-ck roughly follows the release cycle of the official ARCH kernel. The following are requirements for its release:
 
  
*Upstream code
+
=== Release cycle ===
*CK's Patchset
+
 
*BFQ Patchset
+
Linux-ck roughly follows the release cycle of the official ARCH kernel but not only. The following are requirements for a new package release:
*ARCH config/config.x86_64 sets for major version jumps only
+
 
 +
* CK patchset compatible with the current kernel version
 +
* corresponding ARCH kernel must be in existence otherwise it will break other packages i.e. nvidia. See [https://git.archlinux.org/svntogit/packages.git/log/trunk?h=packages/linux git.archlinux.org] for the official {{Pkg|linux}} package
 +
 
 +
=== Package defaults ===
  
=== Package Defaults ===
 
 
There are '''three''' modifications to the config files:
 
There are '''three''' modifications to the config files:
#The options that the ck patchset enable/disable.
+
# The options that the CK patchset enable/disable.
#The options that the BFQ patchset need to compile without user interaction.
+
# The tickrate is set to 100 Hz (CK's recommendation).
#Apply [https://github.com/graysky2/kernel_gcc_patch GCC patch] that enables additional CPU optimizations at compile time (these options are not part of the standard linux-ck package and are only available when the user compiles custom options).
+
# The extra CPU types optionally available to compilation thanks to the [https://github.com/graysky2/kernel_gcc_patch GCC patch].
 +
 
 +
'''All other options are set to the ARCH defaults outlined in the main kernel's config files.''' Of course users are free to edit them.
 +
 
 +
The {{AUR|linux-ck}} package contains an option to switch on the '''nconfig''' config editor (see the section [[#Compile the package from source|below]]).
 +
 
 +
=== Long-Term Support (LTS) CK releases ===
 +
 
 +
In addition to the {{AUR|linux-ck}} package, there are LTS kernel releases patched with the above patchsets as well and with the previously mentioned modifications:
 +
 
 +
* {{AUR|linux-lts-ck}} - The current Arch Linux LTS kernel patched with the CK patchset
 +
 
 +
{{Note|This package is maintained by vishwin, thus pre-compiled versions will not be present in the unofficial ck repo.}}
  
'''All other options are set to the ARCH defaults outlined in the main kernel's config files.'''  Users are of course free to modify them!  The linux-ck package contains an option to switch on the '''nconfig''' config editor (see section below).  For some suggestions, see CK's [http://ck.kolivas.org/patches/bfs/bfs-configuration-faq.txt BFS configuration FAQ].
+
== Installation options ==
  
==Installation Options==
+
{{Note|As with ''any'' additional kernel, users need to manually update their [[boot loader]]'s configuration file in order to make it aware of the new kernel image.}}
{{Note|As with *any* additional kernel, users will need to manually edit their boot loader's config file to make it aware of the new kernel images. For example, users of [[GRUB]] should execute "grub-mkconfig -o /boot/grub/grub.cfg".  Syslinux, GRUB-legacy, etc. will need to be modified as well.}}
 
  
 
Users have two options to get these kernel packages.
 
Users have two options to get these kernel packages.
===1. Compile the Package From Source===
+
 
 +
=== Compile the package from source ===
 +
 
 
The [[AUR]] contains entries for both packages mentioned above.
 
The [[AUR]] contains entries for both packages mentioned above.
  
Users can customize the linux-ck package via tweaks in the PKGBUILD:
+
Users can further customize the linux-ck package via tweaks contained in the PKGBUILD:
  
* Optional nconfig for user specific tweaking.
+
* Optional '''nconfig''' for user specific tweaking.
* Option to compile a minimal set of modules via a make localmodconfig.
+
* Option to compile a minimal set of modules via a make '''localmodconfig'''.
* Option to bypass the standard ARCH config options and simply use the current kernel's .config file.
+
* Option to bypass the standard ARCH config options and simply use the '''current kernel configuration''' file.
 
* Optionally set the [http://algo.ing.unimo.it/people/paolo/disk_sched/ BFQ I/O scheduler] as default.
 
* Optionally set the [http://algo.ing.unimo.it/people/paolo/disk_sched/ BFQ I/O scheduler] as default.
  
More details about these options are provided in the PKGBUILD itself via line comments.  Be sure to read them if compiling from the AUR!
+
More details about these options are provided in the PKGBUILD itself.  Be sure to read them carefully if compiling from AUR!
  
{{Note|There are related PKGBUILDs in the AUR for other common modules unique to linux-ck.  For example {{AUR|nvidia-ck}}, {{AUR|nvidia-304xx-ck}},{{AUR|lirc-ck}}, and {{AUR|broadcom-wl-ck}}.}}
+
{{Note|There are the related PKGBUILDs in AUR for other common kernel modules.  For example {{AUR|nvidia-ck}}, {{AUR|nvidia-304xx-ck}}, {{AUR|nvidia-340xx-ck}}, and {{AUR|broadcom-wl-ck}} to name a few. Alternatively, use the corresponding [[DKMS]] package, for instance install {{pkg|nvidia-dkms}} as described in [[NVIDIA#Custom kernel]].}}
  
===2. Use Pre-Compiled Packages===
+
=== Use pre-compiled packages ===
  
If users would rather not spend the time to compile on their own, an unofficial repo maintained by [[User:Graysky|graysky]] is available to the community.
+
If user prefers to spend no time to compile on their own, the unofficial repo maintained by [[User:Graysky|graysky]] is available to the community. For details, see: [[Repo-ck]].
  
For details, see: [[Repo-ck]].
+
== How to enable the BFQ I/O Scheduler ==
  
== How to Enable the BFQ I/O Scheduler ==
+
{{Note|Do not confuse MuQSS (Multiple Queue Skiplist Scheduler) with BFQ (Budget Fair Queueing). MuQSS is a CPU scheduler and is enabled by default whereas BFQ is an I/O scheduler and must explicitly be enabled in order to use it.}}
  
Budget Fair Queueing is a disk scheduler which allows each process/thread to be assigned a portion of the disk throughput.
+
Budget Fair Queueing is a disk scheduler which allows each process/thread to be assigned a portion of the disk throughput.  Its creator shares the results of many benchmarks ([http://algo.ing.unimo.it/people/paolo/disk_sched/results.php results] and [http://www.youtube.com/watch?v=KhZl9LjCKuU video]) which show the latency performance improvement.
  
=== Globally (for all devices) ===
+
Due to CK's patchset defaults, BFQ is built into [[AUR|linux-ck]] but the above-mentioned scheduler must be enabled manually. User has several options to do that.
If compiling from the AUR, simply set the BFQ flag to yes in the PKGBUILD prior to building.
+
 
 +
=== Enable BFQ for all devices ===
 +
 
 +
If compiling from the AUR, simply set the BFQ flag to "y" in the PKGBUILD prior to building
 
  _BFQ_enable_="y"
 
  _BFQ_enable_="y"
  
If using the repo packages, append "elevator=bfq" to the kernel boot line in {{ic|/boot/grub/menu.lst}} if using grub or in {{ic|/etc/default/grub}} under the '''GRUB_CMDLINE_LINUX_DEFAULT="quiet"''' line followed by rebuilding {{ic|/boot/grub/grub.cfg}} via the standard "grub-mkconfig -o /boot/grub/grub.cfg" command.
+
Users of [[repo-ck]] or those who have not modified the PKGBUILD prior to compile the package can append {{ic|1=elevator=bfq}} to the [[kernel parameters]].
  
=== Selectively (for only specified devices) ===
+
=== Enable BFQ only for specific devices ===
An alternative method is to direct the kernel to use it on a device-by-device basis.  For example, to enable it for {{ic|/dev/sda}} simply:
 
# echo bfq > /sys/block/sda/queue/scheduler
 
  
To confirm, simply ''cat'' the same file:
+
An alternative method is to instruct the kernel at runtime to use BFQ on a device-by-device basis. For configuration examples see the [[Improving performance#Tuning IO schedulers]] section.
# cat /sys/block/sda/queue/scheduler
 
noop deadline cfq [bfq]  
 
  
Note that doing it this way will not survive a reboot.  To make the change automatically at the next system boot, place lines in {{ic|/etc/tmpfiles.d/IO_scheduler.conf}}:
+
== More about MuQSS ==
  
w /sys/block/sda/queue/scheduler - - - - bfq
+
See the [https://lkml.org/lkml/2016/10/29/4 LKML announcement] posted by CK.
  
== Troubleshooting ==
+
=== Check if MuQSS is enabled ===
=== Running Virtualbox with Linux-ck ===
 
Virtualbox works just fine with custom kernels such as Linux-ck ''without'' the need to keep any of the official ARCH kernel-headers packages on the system!
 
  
Don't forget to add users to the ''vboxusers '' group:
+
This start-up message should appear in the kernel ring buffer when MuQSS in enabled:
  # gpasswd -a USERNAME vboxusers
+
  $ dmesg | grep -i muqss
 +
...
 +
MuQSS CPU scheduler v0.120 by Con Kolivas.
  
==== Option 1. Use the Unofficial Repo (Recommended) ====
+
=== MuQSS patched kernels and systemd ===
{{Note|As of 17-Oct-2012, Repo-ck users can enjoy these modules as precompiled packages in the repo itself.  If you built your linux-ck from the AUR you CANNOT USE THE REPO as all packages in the repo are matched groups.}}
 
  
See the [[Repo-ck]] article to setup http://repo-ck.com for pacman to use directly.
+
It is a common mistake to think that MuQSS does not support ''cgroups''. It does but not all the cgroup features (e.g. CPU limiting will not work).
  
==== Option 2. The virtualbox-ck-modules package (Recommended if Linux-ck is Built by You from the AUR) ====
+
== Troubleshooting ==
Install the {{AUR|virtualbox-ck-modules}} package and then install '''virtualbox''' package.
 
  
==== Option 3. Use DKMS (More complicated) ====
+
=== Running VirtualBox with Linux-ck ===
Install '''virtualbox''' with the '''virtualbox-host-dkms''' package.  Then setup dkms as follows:
 
# pacman -S virtualbox virtualbox-host-dkms
 
# dkms install vboxhost/4.2.6
 
  
{{Note|Make sure to substitute the correct version number of virtualbox in the second command.  At the time of writting, 4.2.6 is current.}}
+
VirtualBox works just fine with custom kernels such as Linux-ck ''without'' the need to keep any of the official ARCH kernel headers package on the system.
  
=== Downgrading ===
+
Do not forget to add users to the ''vboxusers '' group:
Users wishing to downgrade to a previous version of linux-ck, have several options:
+
# gpasswd -a USERNAME vboxusers
*Source archives are [http://repo-ck.com/bench.htm available] dating back to linux-ck-3.3.7-1.
 
*[http://pkgbuild.com/git/aur-mirror.git/log/linux-ck AUR.git] holds AUR git commits for linux-ck dating back to linux-ck-2.6.39.3-1.
 
  
=== Forum Support ===
+
==== Use the unofficial repo (recommended if Linux-ck is installed from Repo-ck) ====
Always feel free to open a thread in the forums for support.  Be sure to give the thread a descriptive title to draw attention to the fact that the post relates to the Linux- ck package.
 
  
==A Little About the BFS==
+
{{Note|As of 17-Oct-2012, Repo-ck users can enjoy these modules as pre-compiled packages in the repo itself. If you build Linux-ck from AUR you '''can not use the repo''' as all packages in the repo are matched groups.}}
  
The Brain Fuck Scheduler is a desktop orientated cpu process scheduler with extremely low latencies for excellent interactivity within normal load levels.
+
See the [[Repo-ck]] section to set up it correctly.
  
===BFS Design Goals===
+
==== The virtualbox-ck-host-modules package (recommended if Linux-ck is built from AUR) ====
The BFS has two major design goals:
 
#Achieve excellent desktop interactivity and responsiveness without heuristics and tuning knobs that are difficult to understand, impossible to model and predict the effect of, and when tuned to one workload cause massive detriment to another.
 
#Completely do away with the complex designs of the past for the cpu process scheduler and instead implement one that is very simple in basic design.
 
  
For additional information, see the [[linux-ck#Further_Reading_on_BFS_and_CK_Patchset]] section of this article.
+
Install the {{AUR|virtualbox-ck-host-modules}} package and then install the '''virtualbox''' package.
  
===An Example Video About Queuing Theory===
+
==== Use DKMS (more complicated, recommended for LTS versions) ====
See [http://www.youtube.com/watch?v=F5Ri_HhziI0 this video] about queuing theory for an interesting parallel with
 
supermarket checkouts.  Quote from CK, "the relevance of that video is that BFS uses a single queue, whereas the mainline Linux kernel uses a multiple queue design. The people are tasks, and the checkouts are CPUs. Of course there's a lot more to a CPU scheduler than just the queue design, but I thought this video was very relevant."
 
  
===Some Performance-Based Metrics: BFS vs. CFS===
+
Install '''virtualbox''' with the '''virtualbox-host-dkms''' package. Then setup DKMS as follows:
A major benefit of using the BFS is increased responsiveness. The benefits however, are not limited to desktop feel.  [[User:Graysky|Graysky]] put together some non-responsiveness based benchmarks to compare it to the CFS contained in the "stock" linux kernel.  Seven different machines were used to see if differences exist and, to what degree they scale using performance based metrics. Again, these end-points were never factors in the primary design goals of the bfs. Results were encouraging.  
+
  # pacman -S virtualbox virtualbox-host-dkms
 +
  # dkms install vboxhost/4.3.12
  
For those not wanting to see the full report, here is the conclusion:
+
{{Note|Make sure to substitute the correct version number of virtualbox in the second command. At the time of writing, 4.3.12 is current.}}
Kernels patched with the ck1 patch set including the bfs outperformed the vanilla kernel using the cfs at nearly all the performance-based benchmarks tested. Further study with a larger test set could be conducted, but based on the small test set of 7 PCs evaluated, these increases in process queuing, efficiency/speed are, on the whole, independent of CPU type (mono, dual, quad, hyperthreaded, etc.), CPU architecture (32-bit and 64-bit), 64 bit) and of CPU multiplicity (mono or dual socket).
 
  
Moreover, several "modern" CPUs (Intel C2D and Ci7) that represent common workstations and laptops, consistently outperformed the cfs in the vanilla kernel at all benchmarks.  Efficiency and speed gains were small to moderate.
+
=== Downgrading ===
  
[[http://repo-ck.com/bench/cpu_schedulers_compared.pdf CPU_Schedulers_Compared.pdf]] is available for download.
+
Users wishing to downgrade to a previous version of Linux-ck, have several options:
 +
* Source archives are [http://repo-ck.com/bench.htm available] dating back to linux-ck-3.3.7-1.
 +
* [http://pkgbuild.com/git/aur-mirror.git/log/linux-ck AUR.git] holds AUR git commits for Linux-ck, dating back to linux-ck-2.6.39.3-1.
  
=== Check if Enabled ===
+
=== Forum support ===
This start-up message should appear in the kernel ring buffer when BFS in enabled:
 
# dmesg | grep scheduler
 
...
 
[    0.380500] BFS CPU scheduler v0.420 by Con Kolivas.
 
  
==BFS Myths==
+
Always feel free to open a thread in the forums for support purpose. Be sure to give the thread a descriptive title to draw attention to the fact that the post relates to the Linux-ck package.
===BFS patched kernels CAN in fact use systemd===
 
It is a common mistake to think that bfs does not support cgroups. It does support cgroups, just not all the cgroup features.  Systemd works with BFS patched kernels, though systemd user sessions are broken for now, as some of those missing features are required to start {{ic|systemd --user}}.
 
  
==Further Reading on BFS and CK Patchset==
+
== See also ==
*[http://ck.kolivas.org/patches/bfs/bfs-faq.txt Con Kolivas' White Paper on the BFS]
 
*[http://en.wikipedia.org/wiki/Brain_Fuck_Scheduler Wikipedia's BFS Article]
 
*[http://ck-hack.blogspot.com/ Con Kolivas' Blog]
 
  
==[[Linux-ck/Changelog|Linux-ck Package Changelog]]==
+
* [http://users.tpg.com.au/ckolivas/kernel/ Kernel patch homepage of Con Kolivas]
 +
* [http://ck-hack.blogspot.it/ Con Kolivas' Blog]
 +
* [http://lkml.org/lkml/2009/9/6/136 Con Kolivas' desktop-centric kernel patchset]
 +
* [[wikipedia:Con_Kolivas|Wikipedia's Con Kovalis page]]
 +
* [[wikipedia:Brain_Fuck_Scheduler|Wikipedia's BFS article]]

Latest revision as of 13:59, 20 May 2017

Related articles

General package details

Linux-ckAUR is a package available both in AUR and in the unofficial repo-ck repository that allows users to run a kernel and headers setup patched with Con Kolivas' ck patchset[1], including MuQSS (Multiple Queue Skiplist Scheduler, pronounced mux) which replaces Brain Fuck Scheduler (BFS), his previous work. Many Arch Linux users choose this kernel for its excellent desktop interactivity and responsiveness under any load situation.

Ck patchset is designed for desktop/laptop use but not for servers. It provides low latency environment and works well for 16 CPUs or fewer.

Release cycle

Linux-ck roughly follows the release cycle of the official ARCH kernel but not only. The following are requirements for a new package release:

  • CK patchset compatible with the current kernel version
  • corresponding ARCH kernel must be in existence otherwise it will break other packages i.e. nvidia. See git.archlinux.org for the official linux package

Package defaults

There are three modifications to the config files:

  1. The options that the CK patchset enable/disable.
  2. The tickrate is set to 100 Hz (CK's recommendation).
  3. The extra CPU types optionally available to compilation thanks to the GCC patch.

All other options are set to the ARCH defaults outlined in the main kernel's config files. Of course users are free to edit them.

The linux-ckAUR package contains an option to switch on the nconfig config editor (see the section below).

Long-Term Support (LTS) CK releases

In addition to the linux-ckAUR package, there are LTS kernel releases patched with the above patchsets as well and with the previously mentioned modifications:

  • linux-lts-ckAUR - The current Arch Linux LTS kernel patched with the CK patchset
Note: This package is maintained by vishwin, thus pre-compiled versions will not be present in the unofficial ck repo.

Installation options

Note: As with any additional kernel, users need to manually update their boot loader's configuration file in order to make it aware of the new kernel image.

Users have two options to get these kernel packages.

Compile the package from source

The AUR contains entries for both packages mentioned above.

Users can further customize the linux-ck package via tweaks contained in the PKGBUILD:

  • Optional nconfig for user specific tweaking.
  • Option to compile a minimal set of modules via a make localmodconfig.
  • Option to bypass the standard ARCH config options and simply use the current kernel configuration file.
  • Optionally set the BFQ I/O scheduler as default.

More details about these options are provided in the PKGBUILD itself. Be sure to read them carefully if compiling from AUR!

Note: There are the related PKGBUILDs in AUR for other common kernel modules. For example nvidia-ckAUR, nvidia-304xx-ckAUR, nvidia-340xx-ckAUR, and broadcom-wl-ckAUR to name a few. Alternatively, use the corresponding DKMS package, for instance install nvidia-dkms as described in NVIDIA#Custom kernel.

Use pre-compiled packages

If user prefers to spend no time to compile on their own, the unofficial repo maintained by graysky is available to the community. For details, see: Repo-ck.

How to enable the BFQ I/O Scheduler

Note: Do not confuse MuQSS (Multiple Queue Skiplist Scheduler) with BFQ (Budget Fair Queueing). MuQSS is a CPU scheduler and is enabled by default whereas BFQ is an I/O scheduler and must explicitly be enabled in order to use it.

Budget Fair Queueing is a disk scheduler which allows each process/thread to be assigned a portion of the disk throughput. Its creator shares the results of many benchmarks (results and video) which show the latency performance improvement.

Due to CK's patchset defaults, BFQ is built into linux-ck but the above-mentioned scheduler must be enabled manually. User has several options to do that.

Enable BFQ for all devices

If compiling from the AUR, simply set the BFQ flag to "y" in the PKGBUILD prior to building

_BFQ_enable_="y"

Users of repo-ck or those who have not modified the PKGBUILD prior to compile the package can append elevator=bfq to the kernel parameters.

Enable BFQ only for specific devices

An alternative method is to instruct the kernel at runtime to use BFQ on a device-by-device basis. For configuration examples see the Improving performance#Tuning IO schedulers section.

More about MuQSS

See the LKML announcement posted by CK.

Check if MuQSS is enabled

This start-up message should appear in the kernel ring buffer when MuQSS in enabled:

$ dmesg | grep -i muqss
...
MuQSS CPU scheduler v0.120 by Con Kolivas.

MuQSS patched kernels and systemd

It is a common mistake to think that MuQSS does not support cgroups. It does but not all the cgroup features (e.g. CPU limiting will not work).

Troubleshooting

Running VirtualBox with Linux-ck

VirtualBox works just fine with custom kernels such as Linux-ck without the need to keep any of the official ARCH kernel headers package on the system.

Do not forget to add users to the vboxusers group:

# gpasswd -a USERNAME vboxusers

Use the unofficial repo (recommended if Linux-ck is installed from Repo-ck)

Note: As of 17-Oct-2012, Repo-ck users can enjoy these modules as pre-compiled packages in the repo itself. If you build Linux-ck from AUR you can not use the repo as all packages in the repo are matched groups.

See the Repo-ck section to set up it correctly.

The virtualbox-ck-host-modules package (recommended if Linux-ck is built from AUR)

Install the virtualbox-ck-host-modulesAUR package and then install the virtualbox package.

Use DKMS (more complicated, recommended for LTS versions)

Install virtualbox with the virtualbox-host-dkms package. Then setup DKMS as follows:

# pacman -S virtualbox virtualbox-host-dkms
# dkms install vboxhost/4.3.12
Note: Make sure to substitute the correct version number of virtualbox in the second command. At the time of writing, 4.3.12 is current.

Downgrading

Users wishing to downgrade to a previous version of Linux-ck, have several options:

  • Source archives are available dating back to linux-ck-3.3.7-1.
  • AUR.git holds AUR git commits for Linux-ck, dating back to linux-ck-2.6.39.3-1.

Forum support

Always feel free to open a thread in the forums for support purpose. Be sure to give the thread a descriptive title to draw attention to the fact that the post relates to the Linux-ck package.

See also