Kernel org linux firmware

Built-in firmware¶

Firmware can be built-in to the kernel, this means building the firmware into vmlinux directly, to enable avoiding having to look for firmware from the filesystem. Instead, firmware can be looked for inside the kernel directly. You can enable built-in firmware using the kernel configuration options:

• CONFIG_EXTRA_FIRMWARE
• CONFIG_EXTRA_FIRMWARE_DIR

This should not be confused with CONFIG_FIRMWARE_IN_KERNEL, this is for drivers which enables firmware to be built as part of the kernel build process. This option, CONFIG_FIRMWARE_IN_KERNEL, will build all firmware for all drivers enabled which ship its firmware inside the Linux kernel source tree.

There are a few reasons why you might want to consider building your firmware into the kernel with CONFIG_EXTRA_FIRMWARE though:

• Speed
• Firmware is needed for accessing the boot device, and the user doesn’t want to stuff the firmware into the boot initramfs.

Even if you have these needs there are a few reasons why you may not be able to make use of built-in firmware:

• Legalese — firmware is non-GPL compatible
• Some firmware may be optional
• Firmware upgrades are possible, therefore a new firmware would implicate a complete kernel rebuild.
• Some firmware files may be really large in size. The remote-proc subsystem is an example subsystem which deals with these sorts of firmware
• The firmware may need to be scraped out from some device specific location dynamically, an example is calibration data for for some WiFi chipsets. This calibration data can be unique per sold device.

© Copyright The kernel development community.

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Built-in firmware¶

Firmware can be built-in to the kernel, this means building the firmware into vmlinux directly, to enable avoiding having to look for firmware from the filesystem. Instead, firmware can be looked for inside the kernel directly. You can enable built-in firmware using the kernel configuration options:

• CONFIG_EXTRA_FIRMWARE
• CONFIG_EXTRA_FIRMWARE_DIR

This should not be confused with CONFIG_FIRMWARE_IN_KERNEL, this is for drivers which enables firmware to be built as part of the kernel build process. This option, CONFIG_FIRMWARE_IN_KERNEL, will build all firmware for all drivers enabled which ship its firmware inside the Linux kernel source tree.

There are a few reasons why you might want to consider building your firmware into the kernel with CONFIG_EXTRA_FIRMWARE though:

• Speed
• Firmware is needed for accessing the boot device, and the user doesn’t want to stuff the firmware into the boot initramfs.

Even if you have these needs there are a few reasons why you may not be able to make use of built-in firmware:

• Legalese — firmware is non-GPL compatible
• Some firmware may be optional
• Firmware upgrades are possible, therefore a new firmware would implicate a complete kernel rebuild.
• Some firmware files may be really large in size. The remote-proc subsystem is an example subsystem which deals with these sorts of firmware
• The firmware may need to be scraped out from some device specific location dynamically, an example is calibration data for for some WiFi chipsets. This calibration data can be unique per sold device.

© Copyright The kernel development community.

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The Linux Kernel Archives

There are several main categories into which kernel releases may fall:

Prepatch Prepatch or «RC» kernels are mainline kernel pre-releases that are mostly aimed at other kernel developers and Linux enthusiasts. They must be compiled from source and usually contain new features that must be tested before they can be put into a stable release. Prepatch kernels are maintained and released by Linus Torvalds. Mainline Mainline tree is maintained by Linus Torvalds. It’s the tree where all new features are introduced and where all the exciting new development happens. New mainline kernels are released every 2-3 months. Stable After each mainline kernel is released, it is considered «stable.» Any bug fixes for a stable kernel are backported from the mainline tree and applied by a designated stable kernel maintainer. There are usually only a few bugfix kernel releases until next mainline kernel becomes available — unless it is designated a «longterm maintenance kernel.» Stable kernel updates are released on as-needed basis, usually once a week. Longterm There are usually several «longterm maintenance» kernel releases provided for the purposes of backporting bugfixes for older kernel trees. Only important bugfixes are applied to such kernels and they don’t usually see very frequent releases, especially for older trees.

Longterm release kernels

Version	Maintainer	Released	Projected EOL
5.10	Greg Kroah-Hartman & Sasha Levin	2020-12-13	Dec, 2026
5.4	Greg Kroah-Hartman & Sasha Levin	2019-11-24	Dec, 2025
4.19	Greg Kroah-Hartman & Sasha Levin	2018-10-22	Dec, 2024
4.14	Greg Kroah-Hartman & Sasha Levin	2017-11-12	Jan, 2024
4.9	Greg Kroah-Hartman & Sasha Levin	2016-12-11	Jan, 2023
4.4	Greg Kroah-Hartman & Sasha Levin	2016-01-10	Feb, 2022

Distribution kernels

Many Linux distributions provide their own «longterm maintenance» kernels that may or may not be based on those maintained by kernel developers. These kernel releases are not hosted at kernel.org and kernel developers can provide no support for them.

It is easy to tell if you are running a distribution kernel. Unless you downloaded, compiled and installed your own version of kernel from kernel.org, you are running a distribution kernel. To find out the version of your kernel, run uname -r :

If you see anything at all after the dash, you are running a distribution kernel. Please use the support channels offered by your distribution vendor to obtain kernel support.

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The Linux Kernel Archives

What is Linux?

Linux is a clone of the operating system Unix, written from scratch by Linus Torvalds with assistance from a loosely-knit team of hackers across the Net. It aims towards POSIX and Single UNIX Specification compliance.

It has all the features you would expect in a modern fully-fledged Unix, including true multitasking, virtual memory, shared libraries, demand loading, shared copy-on-write executables, proper memory management, and multistack networking including IPv4 and IPv6.

Although originally developed first for 32-bit x86-based PCs (386 or higher), today Linux also runs on a multitude of other processor architectures, in both 32- and 64-bit variants.

New to Linux?

If you’re new to Linux, you don’t want to download the kernel, which is just a component in a working Linux system. Instead, you want what is called a distribution of Linux, which is a complete Linux system. There are numerous distributions available for download on the Internet as well as for purchase from various vendors; some are general-purpose, and some are optimized for specific uses. We currently have mirrors of several distributions available at https://mirrors.kernel.org/.

Note, however, that most distributions are very large (several gigabytes), so unless you have a fast Internet link you may want to save yourself some hassle and purchase a CD-ROM with a distribution; such CD-ROMs are available from a number of vendors.

Mailing lists

The Linux kernel is discussed on the linux-kernel mailing list at vger.kernel.org. Please read the FAQ before subscribing.

Although there is no official archive site, unofficial archives of the list can be found at:

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The Linux Kernel Archives

If you have questions, comments or concerns about the F.A.Q. please contact us at webmaster@kernel.org.

Is Linux Kernel Free Software?

Linux kernel is released under GNU GPL version 2 and is therefore Free Software as defined by the Free Software Foundation. You may read the entire copy of the license in the COPYING file distributed with each release of the Linux kernel.

What does «stable/EOL» and «longterm» mean?

As kernels move from the «mainline» into the «stable» category, two things can happen:

1. They can reach «End of Life» after a few bugfix revisions, which means that kernel maintainers will release no more bugfixes for this kernel version, or
2. They can be put into «longterm» maintenance, which means that maintainers will provide bugfixes for this kernel revision for a much longer period of time.

If the kernel version you are using is marked «EOL,» you should consider upgrading to the next major version as there will be no more bugfixes provided for the kernel version you are using.

Please check the Releases page for more info.

Why is an LTS kernel marked as «stable» on the front page?

Long-term support («LTS») kernels announced on the Releases page will be marked as «stable» on the front page if there are no other current stable kernel releases. This is done to avoid breaking automated parsers monitoring kernel.org with an expectation that there will always be a kernel release marked as «stable.»

Linus has tagged a new release, but it’s not listed on the front page!

Linus Torvalds PGP-signs git repository tags for all new mainline kernel releases, however a separate set of PGP signatures needs to be generated by the stable release team in order to create downloadable tarballs. Due to timezone differences between Linus and the members of the stable team, there is usually a delay of several hours between when the new mainline release is tagged and when PGP-signed tarballs become available. The front page is updated once that process is completed.

Is there an RSS feed for the latest kernel version?

We also publish a .json file with the latest release information, which you can pull from here: https://www.kernel.org/releases.json.

Why are there files that are dated tomorrow?

All timestamps on kernel.org are in UTC (Coordinated Universal Time). If you live in the western hemisphere your local time lags behind UTC. Under Linux/Unix, type date -u to get the current time in UTC.

Can I get an account on kernel.org?

Kernel.org accounts are usually reserved for subsystem maintainers or high-profile developers. It is absolutely not necessary to have an account on kernel.org to contribute to the development of the Linux kernel, unless you submit pull requests directly to Linus.

If you are listed in the MAINTAINERS file or have reasons to believe you should have an account on kernel.org because of the amount of your contributions, please refer to the accounts wiki page for the procedure to follow.

I have cool project X, can you guys mirror it for me?

Probably not. Kernel.org deals with the Linux kernel, various distributions of the kernel and larger repositories of packages. We do not mirror individual projects, software, etc as we feel there are better places providing mirrors for those kinds of repositories. If you feel that kernel.org should mirror your project, please contact ftpadmin@kernel.org with the following information:

• name
• project name
• project website
• detailed project description
• reason for wanting us to mirror

The Kernel.org admin team will then review your request and talk to you about it. As with any kind of account on kernel.org it’s up to the discretion of the admin team.

How does kernel.org provide its users access to the git trees?

We are using an access control system called gitolite, originally written and maintained by Sitaram Chamarty. We chose gitolite for a number of reasons:

• Limiting of ssh access to the system
• Fine grained control over repository access
• Well maintained and supported code base
• Responsive development
• Broad and diverse install base

As well at the time of deployment the code had undergone an external code review.

How do I create an -rc kernel? I get «Reversed patch detected!»

-rc kernel patches are generated from the base stable release.

For example: to create the 2.6.14-rc5 kernel, you must:

• download 2.6.13 (not 2.6.13.4)
• and then apply the 2.6.14-rc5 patch.

Yes, you want 2.6.13, not 2.6.14. Remember, that’s an -rc kernel, as in, 2.6.14 doesn’t exist yet. 🙂

Where can I find kernel 2.4.20-3.16?

Kernel version numbers of this form are distribution kernels, meaning they are modified kernels produced by distributions. Please contact the relevant distributor; or check out https://mirrors.kernel.org/.

See the Releases page for more info on distribution kernels.

I need help building/patching/fixing Linux kernel/modules/drivers!

Please see the Kernel Newbies website.

There is also a wealth of knowledge on many topics involving Linux at The Linux Documentation Project (http://www.tldp.org)

For finding or reporting bugs, look through the archives for the various Linux mailing lists, and if no specific list seems appropriate, try the browsing the Linux Kernel Mailing List.

What happened to ftp.kernel.org?

FTP service was terminated on March 1, 2017. All content that used to be available via ftp.kernel.org can be accessed by browsing https://www.kernel.org/pub/. If you would like to use a command-line tool for accessing these files, you can do so with lftp:

When will the next kernel be released?

The next kernel will be released when it is ready. There is no strict timeline for making releases, but if you really need an educated guess, visit the Linux kernel PHB Crystal Ball — it tries to provide a ballpark guess based on previous kernel release schedule.

What will go into the next release?

It is hard to predict with certainty, but you can either take a peek at linux-next or read the Linux Weather Forecast, where Jonathan Corbet provides a broad forecast of what will likely be included into the next mainline release.

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