Documentation

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The Linux kernel backports project aims at backporting Linux ''upstream'' device drivers for usage on older kernels. The point of the project is to provide a central mechanism for backporting device drivers for ''any'' subsystem. The backports project shall '''never''' include proprietary drivers and by design does not allow usage of itself with proprietary drivers. Every backports release has been test compiled ''for usage'' against  all supported kernels, currently 2.6.24 - latest. Always use the latest ''stable'' available release.
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The Backports Project aims to backport current Linux '''upstream''' device drivers for use with older kernels. The objective (1) is to provide a central mechanism for backporting the device drivers of ''any'' subsystem, thereby enabling (2) ''both'' users '''and''' developers to always focus on upstream Linux kernel development.
  
<h2>Release types</h2>
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The project shall '''never''' include proprietary drivers, and is designed to disallow its use with proprietary drivers.
  
Both daily snapshots based on [http://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git linux-next], and stable releases based [http://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git Linux's stable releases] are provided.
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Every backports release has been test compiled ''for usage'' against all supported kernels. The oldest release is (currently) 3.0.
  
<h2>Usage guide</h2>
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Linux kernel releases can become deprecated. You are encouraged to use supported stable kernels as listed on [http://kernel.org kernel.org].
  
Building backports follows the same build mechanism as building the Linux kernel.
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= Workflows =
  
<pre>
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Backports provides users with a choice of two workflows:
# as a user
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make menuconfig
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make
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# as root
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make install
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# reboot and enjoy
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</pre>
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Its understood users may not how to configure the backports package, just like they may not know how to configure the Linux kernel, so a short cut is provided with default configuration files that can be used to only build their drivers / subsystems of interest.
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# '''kernel integration mode''' ([[Documentation/integration|documentation]])
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#* future kernel source tree and older kernel source tree must be present on the same machine at the same time
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#* backports suite '''integrates''' the subsystems/drivers of the future kernel directly into the older kernel
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# '''package releases mode''' ([[Documentation/packaging|documentation]])
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#* future kernel source tree and older kernel source tree do not need to be present on the same machine at the same time
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#* on machine hosting future kernel source tree, backport package is generated
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#* on machine hosting older kernel, backport package is built out-of-tree against older kernel
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#* backport package is loosely akin to a patch file
  
<pre>
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= Backported Subsystems =
make defconfig-help
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</pre>
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If you use this option just use the 'make defconf-option' in replacement for ''make menuconfig'' above. For example to compile all DRM drivers:
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Device drivers are available for the following subsystems:
  
<pre>
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* Ethernet
# as a user
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* Wireless
make defconfig-drm
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* Bluetooth
make
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* NFC
# as root
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* ieee802154
make install
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* Media
</pre>
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* Regulator
  
Note that there are only default configuration files written for a few drivers while the project actually backports over 830 device drivers, the reason we have default configuration files for a few drivers is simply because developer have provided a default config options for them. What we really need is a 'make localmodconfig' support but that will take a while given that it involves mapping older kernel configs to newer kernel configs (which likely would be welcomed upstream as well).
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= Backported Drivers =
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Whether or not a device driver is available from a subsytem will depend on whether or not a developer decided to backport it '''and''' if the device driver is backported down to the kernel you are on. If you see the driver on '''make menuconfig''' it means you can use it. An alternative is to look at the git tree [https://git.kernel.org/cgit/linux/kernel/git/mcgrof/backports.git/tree/dependencies dependencies] file. Note that the [https://git.kernel.org/cgit/linux/kernel/git/mcgrof/backports.git/tree/dependencies dependencies] '''does not''' exist on a final release, it only exists on the development git tree and the one linked here is the one on the master branch -- you should look at the [https://git.kernel.org/cgit/linux/kernel/git/mcgrof/backports.git/refs/ release branches] for their respective dependencies file if using an older release. Someone is welcome to come up with a fancy page that provides the device driver <--> kernel dependency map page. If a device driver is available on '''make menuconfig''' but is not listed on the [https://git.kernel.org/cgit/linux/kernel/git/mcgrof/backports.git/tree/dependencies dependencies] file it means it is available for usage on all supported kernel.
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Users should just install what they ''know'' they need, if not sure don't enable a driver. Typically Linux distributions would use the backports project and build modules for you and you'd have a backports package available for your distribution.
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[[File:88x31.png‎]] - This text is licensed under a [https://creativecommons.org/licenses/by-sa/3.0/ Creative Commons Attribution-ShareAlike 3.0 Unported License].

Latest revision as of 21:38, 21 July 2017

The Backports Project aims to backport current Linux upstream device drivers for use with older kernels. The objective (1) is to provide a central mechanism for backporting the device drivers of any subsystem, thereby enabling (2) both users and developers to always focus on upstream Linux kernel development.

The project shall never include proprietary drivers, and is designed to disallow its use with proprietary drivers.

Every backports release has been test compiled for usage against all supported kernels. The oldest release is (currently) 3.0.

Linux kernel releases can become deprecated. You are encouraged to use supported stable kernels as listed on kernel.org.

[edit] Workflows

Backports provides users with a choice of two workflows:

  1. kernel integration mode (documentation)
    • future kernel source tree and older kernel source tree must be present on the same machine at the same time
    • backports suite integrates the subsystems/drivers of the future kernel directly into the older kernel
  2. package releases mode (documentation)
    • future kernel source tree and older kernel source tree do not need to be present on the same machine at the same time
    • on machine hosting future kernel source tree, backport package is generated
    • on machine hosting older kernel, backport package is built out-of-tree against older kernel
    • backport package is loosely akin to a patch file

[edit] Backported Subsystems

Device drivers are available for the following subsystems:

  • Ethernet
  • Wireless
  • Bluetooth
  • NFC
  • ieee802154
  • Media
  • Regulator

[edit] Backported Drivers

Whether or not a device driver is available from a subsytem will depend on whether or not a developer decided to backport it and if the device driver is backported down to the kernel you are on. If you see the driver on make menuconfig it means you can use it. An alternative is to look at the git tree dependencies file. Note that the dependencies does not exist on a final release, it only exists on the development git tree and the one linked here is the one on the master branch -- you should look at the release branches for their respective dependencies file if using an older release. Someone is welcome to come up with a fancy page that provides the device driver <--> kernel dependency map page. If a device driver is available on make menuconfig but is not listed on the dependencies file it means it is available for usage on all supported kernel.

Users should just install what they know they need, if not sure don't enable a driver. Typically Linux distributions would use the backports project and build modules for you and you'd have a backports package available for your distribution.


88x31.png - This text is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.

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