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authorLibravatar Linus Torvalds <torvalds@linux-foundation.org>2023-02-21 18:24:12 -0800
committerLibravatar Linus Torvalds <torvalds@linux-foundation.org>2023-02-21 18:24:12 -0800
commit5b7c4cabbb65f5c469464da6c5f614cbd7f730f2 (patch)
treecc5c2d0a898769fd59549594fedb3ee6f84e59a0 /Documentation/process/license-rules.rst
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Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-nextgrafted
Pull networking updates from Jakub Kicinski: "Core: - Add dedicated kmem_cache for typical/small skb->head, avoid having to access struct page at kfree time, and improve memory use. - Introduce sysctl to set default RPS configuration for new netdevs. - Define Netlink protocol specification format which can be used to describe messages used by each family and auto-generate parsers. Add tools for generating kernel data structures and uAPI headers. - Expose all net/core sysctls inside netns. - Remove 4s sleep in netpoll if carrier is instantly detected on boot. - Add configurable limit of MDB entries per port, and port-vlan. - Continue populating drop reasons throughout the stack. - Retire a handful of legacy Qdiscs and classifiers. Protocols: - Support IPv4 big TCP (TSO frames larger than 64kB). - Add IP_LOCAL_PORT_RANGE socket option, to control local port range on socket by socket basis. - Track and report in procfs number of MPTCP sockets used. - Support mixing IPv4 and IPv6 flows in the in-kernel MPTCP path manager. - IPv6: don't check net.ipv6.route.max_size and rely on garbage collection to free memory (similarly to IPv4). - Support Penultimate Segment Pop (PSP) flavor in SRv6 (RFC8986). - ICMP: add per-rate limit counters. - Add support for user scanning requests in ieee802154. - Remove static WEP support. - Support minimal Wi-Fi 7 Extremely High Throughput (EHT) rate reporting. - WiFi 7 EHT channel puncturing support (client & AP). BPF: - Add a rbtree data structure following the "next-gen data structure" precedent set by recently added linked list, that is, by using kfunc + kptr instead of adding a new BPF map type. - Expose XDP hints via kfuncs with initial support for RX hash and timestamp metadata. - Add BPF_F_NO_TUNNEL_KEY extension to bpf_skb_set_tunnel_key to better support decap on GRE tunnel devices not operating in collect metadata. - Improve x86 JIT's codegen for PROBE_MEM runtime error checks. - Remove the need for trace_printk_lock for bpf_trace_printk and bpf_trace_vprintk helpers. - Extend libbpf's bpf_tracing.h support for tracing arguments of kprobes/uprobes and syscall as a special case. - Significantly reduce the search time for module symbols by livepatch and BPF. - Enable cpumasks to be used as kptrs, which is useful for tracing programs tracking which tasks end up running on which CPUs in different time intervals. - Add support for BPF trampoline on s390x and riscv64. - Add capability to export the XDP features supported by the NIC. - Add __bpf_kfunc tag for marking kernel functions as kfuncs. - Add cgroup.memory=nobpf kernel parameter option to disable BPF memory accounting for container environments. Netfilter: - Remove the CLUSTERIP target. It has been marked as obsolete for years, and we still have WARN splats wrt races of the out-of-band /proc interface installed by this target. - Add 'destroy' commands to nf_tables. They are identical to the existing 'delete' commands, but do not return an error if the referenced object (set, chain, rule...) did not exist. Driver API: - Improve cpumask_local_spread() locality to help NICs set the right IRQ affinity on AMD platforms. - Separate C22 and C45 MDIO bus transactions more clearly. - Introduce new DCB table to control DSCP rewrite on egress. - Support configuration of Physical Layer Collision Avoidance (PLCA) Reconciliation Sublayer (RS) (802.3cg-2019). Modern version of shared medium Ethernet. - Support for MAC Merge layer (IEEE 802.3-2018 clause 99). Allowing preemption of low priority frames by high priority frames. - Add support for controlling MACSec offload using netlink SET. - Rework devlink instance refcounts to allow registration and de-registration under the instance lock. Split the code into multiple files, drop some of the unnecessarily granular locks and factor out common parts of netlink operation handling. - Add TX frame aggregation parameters (for USB drivers). - Add a new attr TCA_EXT_WARN_MSG to report TC (offload) warning messages with notifications for debug. - Allow offloading of UDP NEW connections via act_ct. - Add support for per action HW stats in TC. - Support hardware miss to TC action (continue processing in SW from a specific point in the action chain). - Warn if old Wireless Extension user space interface is used with modern cfg80211/mac80211 drivers. Do not support Wireless Extensions for Wi-Fi 7 devices at all. Everyone should switch to using nl80211 interface instead. - Improve the CAN bit timing configuration. Use extack to return error messages directly to user space, update the SJW handling, including the definition of a new default value that will benefit CAN-FD controllers, by increasing their oscillator tolerance. New hardware / drivers: - Ethernet: - nVidia BlueField-3 support (control traffic driver) - Ethernet support for imx93 SoCs - Motorcomm yt8531 gigabit Ethernet PHY - onsemi NCN26000 10BASE-T1S PHY (with support for PLCA) - Microchip LAN8841 PHY (incl. cable diagnostics and PTP) - Amlogic gxl MDIO mux - WiFi: - RealTek RTL8188EU (rtl8xxxu) - Qualcomm Wi-Fi 7 devices (ath12k) - CAN: - Renesas R-Car V4H Drivers: - Bluetooth: - Set Per Platform Antenna Gain (PPAG) for Intel controllers. - Ethernet NICs: - Intel (1G, igc): - support TSN / Qbv / packet scheduling features of i226 model - Intel (100G, ice): - use GNSS subsystem instead of TTY - multi-buffer XDP support - extend support for GPIO pins to E823 devices - nVidia/Mellanox: - update the shared buffer configuration on PFC commands - implement PTP adjphase function for HW offset control - TC support for Geneve and GRE with VF tunnel offload - more efficient crypto key management method - multi-port eswitch support - Netronome/Corigine: - add DCB IEEE support - support IPsec offloading for NFP3800 - Freescale/NXP (enetc): - support XDP_REDIRECT for XDP non-linear buffers - improve reconfig, avoid link flap and waiting for idle - support MAC Merge layer - Other NICs: - sfc/ef100: add basic devlink support for ef100 - ionic: rx_push mode operation (writing descriptors via MMIO) - bnxt: use the auxiliary bus abstraction for RDMA - r8169: disable ASPM and reset bus in case of tx timeout - cpsw: support QSGMII mode for J721e CPSW9G - cpts: support pulse-per-second output - ngbe: add an mdio bus driver - usbnet: optimize usbnet_bh() by avoiding unnecessary queuing - r8152: handle devices with FW with NCM support - amd-xgbe: support 10Mbps, 2.5GbE speeds and rx-adaptation - virtio-net: support multi buffer XDP - virtio/vsock: replace virtio_vsock_pkt with sk_buff - tsnep: XDP support - Ethernet high-speed switches: - nVidia/Mellanox (mlxsw): - add support for latency TLV (in FW control messages) - Microchip (sparx5): - separate explicit and implicit traffic forwarding rules, make the implicit rules always active - add support for egress DSCP rewrite - IS0 VCAP support (Ingress Classification) - IS2 VCAP filters (protos, L3 addrs, L4 ports, flags, ToS etc.) - ES2 VCAP support (Egress Access Control) - support for Per-Stream Filtering and Policing (802.1Q, 8.6.5.1) - Ethernet embedded switches: - Marvell (mv88e6xxx): - add MAB (port auth) offload support - enable PTP receive for mv88e6390 - NXP (ocelot): - support MAC Merge layer - support for the the vsc7512 internal copper phys - Microchip: - lan9303: convert to PHYLINK - lan966x: support TC flower filter statistics - lan937x: PTP support for KSZ9563/KSZ8563 and LAN937x - lan937x: support Credit Based Shaper configuration - ksz9477: support Energy Efficient Ethernet - other: - qca8k: convert to regmap read/write API, use bulk operations - rswitch: Improve TX timestamp accuracy - Intel WiFi (iwlwifi): - EHT (Wi-Fi 7) rate reporting - STEP equalizer support: transfer some STEP (connection to radio on platforms with integrated wifi) related parameters from the BIOS to the firmware. - Qualcomm 802.11ax WiFi (ath11k): - IPQ5018 support - Fine Timing Measurement (FTM) responder role support - channel 177 support - MediaTek WiFi (mt76): - per-PHY LED support - mt7996: EHT (Wi-Fi 7) support - Wireless Ethernet Dispatch (WED) reset support - switch to using page pool allocator - RealTek WiFi (rtw89): - support new version of Bluetooth co-existance - Mobile: - rmnet: support TX aggregation" * tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1872 commits) page_pool: add a comment explaining the fragment counter usage net: ethtool: fix __ethtool_dev_mm_supported() implementation ethtool: pse-pd: Fix double word in comments xsk: add linux/vmalloc.h to xsk.c sefltests: netdevsim: wait for devlink instance after netns removal selftest: fib_tests: Always cleanup before exit net/mlx5e: Align IPsec ASO result memory to be as required by hardware net/mlx5e: TC, Set CT miss to the specific ct action instance net/mlx5e: Rename CHAIN_TO_REG to MAPPED_OBJ_TO_REG net/mlx5: Refactor tc miss handling to a single function net/mlx5: Kconfig: Make tc offload depend on tc skb extension net/sched: flower: Support hardware miss to tc action net/sched: flower: Move filter handle initialization earlier net/sched: cls_api: Support hardware miss to tc action net/sched: Rename user cookie and act cookie sfc: fix builds without CONFIG_RTC_LIB sfc: clean up some inconsistent indentings net/mlx4_en: Introduce flexible array to silence overflow warning net: lan966x: Fix possible deadlock inside PTP net/ulp: Remove redundant ->clone() test in inet_clone_ulp(). ...
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+.. SPDX-License-Identifier: GPL-2.0
+
+.. _kernel_licensing:
+
+Linux kernel licensing rules
+============================
+
+The Linux Kernel is provided under the terms of the GNU General Public
+License version 2 only (GPL-2.0), as provided in LICENSES/preferred/GPL-2.0,
+with an explicit syscall exception described in
+LICENSES/exceptions/Linux-syscall-note, as described in the COPYING file.
+
+This documentation file provides a description of how each source file
+should be annotated to make its license clear and unambiguous.
+It doesn't replace the Kernel's license.
+
+The license described in the COPYING file applies to the kernel source
+as a whole, though individual source files can have a different license
+which is required to be compatible with the GPL-2.0::
+
+ GPL-1.0+ : GNU General Public License v1.0 or later
+ GPL-2.0+ : GNU General Public License v2.0 or later
+ LGPL-2.0 : GNU Library General Public License v2 only
+ LGPL-2.0+ : GNU Library General Public License v2 or later
+ LGPL-2.1 : GNU Lesser General Public License v2.1 only
+ LGPL-2.1+ : GNU Lesser General Public License v2.1 or later
+
+Aside from that, individual files can be provided under a dual license,
+e.g. one of the compatible GPL variants and alternatively under a
+permissive license like BSD, MIT etc.
+
+The User-space API (UAPI) header files, which describe the interface of
+user-space programs to the kernel are a special case. According to the
+note in the kernel COPYING file, the syscall interface is a clear boundary,
+which does not extend the GPL requirements to any software which uses it to
+communicate with the kernel. Because the UAPI headers must be includable
+into any source files which create an executable running on the Linux
+kernel, the exception must be documented by a special license expression.
+
+The common way of expressing the license of a source file is to add the
+matching boilerplate text into the top comment of the file. Due to
+formatting, typos etc. these "boilerplates" are hard to validate for
+tools which are used in the context of license compliance.
+
+An alternative to boilerplate text is the use of Software Package Data
+Exchange (SPDX) license identifiers in each source file. SPDX license
+identifiers are machine parsable and precise shorthands for the license
+under which the content of the file is contributed. SPDX license
+identifiers are managed by the SPDX Workgroup at the Linux Foundation and
+have been agreed on by partners throughout the industry, tool vendors, and
+legal teams. For further information see https://spdx.org/
+
+The Linux kernel requires the precise SPDX identifier in all source files.
+The valid identifiers used in the kernel are explained in the section
+`License identifiers`_ and have been retrieved from the official SPDX
+license list at https://spdx.org/licenses/ along with the license texts.
+
+License identifier syntax
+-------------------------
+
+1. Placement:
+
+ The SPDX license identifier in kernel files shall be added at the first
+ possible line in a file which can contain a comment. For the majority
+ of files this is the first line, except for scripts which require the
+ '#!PATH_TO_INTERPRETER' in the first line. For those scripts the SPDX
+ identifier goes into the second line.
+
+|
+
+2. Style:
+
+ The SPDX license identifier is added in form of a comment. The comment
+ style depends on the file type::
+
+ C source: // SPDX-License-Identifier: <SPDX License Expression>
+ C header: /* SPDX-License-Identifier: <SPDX License Expression> */
+ ASM: /* SPDX-License-Identifier: <SPDX License Expression> */
+ scripts: # SPDX-License-Identifier: <SPDX License Expression>
+ .rst: .. SPDX-License-Identifier: <SPDX License Expression>
+ .dts{i}: // SPDX-License-Identifier: <SPDX License Expression>
+
+ If a specific tool cannot handle the standard comment style, then the
+ appropriate comment mechanism which the tool accepts shall be used. This
+ is the reason for having the "/\* \*/" style comment in C header
+ files. There was build breakage observed with generated .lds files where
+ 'ld' failed to parse the C++ comment. This has been fixed by now, but
+ there are still older assembler tools which cannot handle C++ style
+ comments.
+
+|
+
+3. Syntax:
+
+ A <SPDX License Expression> is either an SPDX short form license
+ identifier found on the SPDX License List, or the combination of two
+ SPDX short form license identifiers separated by "WITH" when a license
+ exception applies. When multiple licenses apply, an expression consists
+ of keywords "AND", "OR" separating sub-expressions and surrounded by
+ "(", ")" .
+
+ License identifiers for licenses like [L]GPL with the 'or later' option
+ are constructed by using a "+" for indicating the 'or later' option.::
+
+ // SPDX-License-Identifier: GPL-2.0+
+ // SPDX-License-Identifier: LGPL-2.1+
+
+ WITH should be used when there is a modifier to a license needed.
+ For example, the linux kernel UAPI files use the expression::
+
+ // SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note
+ // SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note
+
+ Other examples using WITH exceptions found in the kernel are::
+
+ // SPDX-License-Identifier: GPL-2.0 WITH mif-exception
+ // SPDX-License-Identifier: GPL-2.0+ WITH GCC-exception-2.0
+
+ Exceptions can only be used with particular License identifiers. The
+ valid License identifiers are listed in the tags of the exception text
+ file. For details see the point `Exceptions`_ in the chapter `License
+ identifiers`_.
+
+ OR should be used if the file is dual licensed and only one license is
+ to be selected. For example, some dtsi files are available under dual
+ licenses::
+
+ // SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
+
+ Examples from the kernel for license expressions in dual licensed files::
+
+ // SPDX-License-Identifier: GPL-2.0 OR MIT
+ // SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+ // SPDX-License-Identifier: GPL-2.0 OR Apache-2.0
+ // SPDX-License-Identifier: GPL-2.0 OR MPL-1.1
+ // SPDX-License-Identifier: (GPL-2.0 WITH Linux-syscall-note) OR MIT
+ // SPDX-License-Identifier: GPL-1.0+ OR BSD-3-Clause OR OpenSSL
+
+ AND should be used if the file has multiple licenses whose terms all
+ apply to use the file. For example, if code is inherited from another
+ project and permission has been given to put it in the kernel, but the
+ original license terms need to remain in effect::
+
+ // SPDX-License-Identifier: (GPL-2.0 WITH Linux-syscall-note) AND MIT
+
+ Another other example where both sets of license terms need to be
+ adhered to is::
+
+ // SPDX-License-Identifier: GPL-1.0+ AND LGPL-2.1+
+
+License identifiers
+-------------------
+
+The licenses currently used, as well as the licenses for code added to the
+kernel, can be broken down into:
+
+1. _`Preferred licenses`:
+
+ Whenever possible these licenses should be used as they are known to be
+ fully compatible and widely used. These licenses are available from the
+ directory::
+
+ LICENSES/preferred/
+
+ in the kernel source tree.
+
+ The files in this directory contain the full license text and
+ `Metatags`_. The file names are identical to the SPDX license
+ identifier which shall be used for the license in source files.
+
+ Examples::
+
+ LICENSES/preferred/GPL-2.0
+
+ Contains the GPL version 2 license text and the required metatags::
+
+ LICENSES/preferred/MIT
+
+ Contains the MIT license text and the required metatags
+
+ _`Metatags`:
+
+ The following meta tags must be available in a license file:
+
+ - Valid-License-Identifier:
+
+ One or more lines which declare which License Identifiers are valid
+ inside the project to reference this particular license text. Usually
+ this is a single valid identifier, but e.g. for licenses with the 'or
+ later' options two identifiers are valid.
+
+ - SPDX-URL:
+
+ The URL of the SPDX page which contains additional information related
+ to the license.
+
+ - Usage-Guidance:
+
+ Freeform text for usage advice. The text must include correct examples
+ for the SPDX license identifiers as they should be put into source
+ files according to the `License identifier syntax`_ guidelines.
+
+ - License-Text:
+
+ All text after this tag is treated as the original license text
+
+ File format examples::
+
+ Valid-License-Identifier: GPL-2.0
+ Valid-License-Identifier: GPL-2.0+
+ SPDX-URL: https://spdx.org/licenses/GPL-2.0.html
+ Usage-Guide:
+ To use this license in source code, put one of the following SPDX
+ tag/value pairs into a comment according to the placement
+ guidelines in the licensing rules documentation.
+ For 'GNU General Public License (GPL) version 2 only' use:
+ SPDX-License-Identifier: GPL-2.0
+ For 'GNU General Public License (GPL) version 2 or any later version' use:
+ SPDX-License-Identifier: GPL-2.0+
+ License-Text:
+ Full license text
+
+ ::
+
+ SPDX-License-Identifier: MIT
+ SPDX-URL: https://spdx.org/licenses/MIT.html
+ Usage-Guide:
+ To use this license in source code, put the following SPDX
+ tag/value pair into a comment according to the placement
+ guidelines in the licensing rules documentation.
+ SPDX-License-Identifier: MIT
+ License-Text:
+ Full license text
+
+|
+
+2. Deprecated licenses:
+
+ These licenses should only be used for existing code or for importing
+ code from a different project. These licenses are available from the
+ directory::
+
+ LICENSES/deprecated/
+
+ in the kernel source tree.
+
+ The files in this directory contain the full license text and
+ `Metatags`_. The file names are identical to the SPDX license
+ identifier which shall be used for the license in source files.
+
+ Examples::
+
+ LICENSES/deprecated/ISC
+
+ Contains the Internet Systems Consortium license text and the required
+ metatags::
+
+ LICENSES/deprecated/GPL-1.0
+
+ Contains the GPL version 1 license text and the required metatags.
+
+ Metatags:
+
+ The metatag requirements for 'other' licenses are identical to the
+ requirements of the `Preferred licenses`_.
+
+ File format example::
+
+ Valid-License-Identifier: ISC
+ SPDX-URL: https://spdx.org/licenses/ISC.html
+ Usage-Guide:
+ Usage of this license in the kernel for new code is discouraged
+ and it should solely be used for importing code from an already
+ existing project.
+ To use this license in source code, put the following SPDX
+ tag/value pair into a comment according to the placement
+ guidelines in the licensing rules documentation.
+ SPDX-License-Identifier: ISC
+ License-Text:
+ Full license text
+
+|
+
+3. Dual Licensing Only
+
+ These licenses should only be used to dual license code with another
+ license in addition to a preferred license. These licenses are available
+ from the directory::
+
+ LICENSES/dual/
+
+ in the kernel source tree.
+
+ The files in this directory contain the full license text and
+ `Metatags`_. The file names are identical to the SPDX license
+ identifier which shall be used for the license in source files.
+
+ Examples::
+
+ LICENSES/dual/MPL-1.1
+
+ Contains the Mozilla Public License version 1.1 license text and the
+ required metatags::
+
+ LICENSES/dual/Apache-2.0
+
+ Contains the Apache License version 2.0 license text and the required
+ metatags.
+
+ Metatags:
+
+ The metatag requirements for 'other' licenses are identical to the
+ requirements of the `Preferred licenses`_.
+
+ File format example::
+
+ Valid-License-Identifier: MPL-1.1
+ SPDX-URL: https://spdx.org/licenses/MPL-1.1.html
+ Usage-Guide:
+ Do NOT use. The MPL-1.1 is not GPL2 compatible. It may only be used for
+ dual-licensed files where the other license is GPL2 compatible.
+ If you end up using this it MUST be used together with a GPL2 compatible
+ license using "OR".
+ To use the Mozilla Public License version 1.1 put the following SPDX
+ tag/value pair into a comment according to the placement guidelines in
+ the licensing rules documentation:
+ SPDX-License-Identifier: MPL-1.1
+ License-Text:
+ Full license text
+
+|
+
+4. _`Exceptions`:
+
+ Some licenses can be amended with exceptions which grant certain rights
+ which the original license does not. These exceptions are available
+ from the directory::
+
+ LICENSES/exceptions/
+
+ in the kernel source tree. The files in this directory contain the full
+ exception text and the required `Exception Metatags`_.
+
+ Examples::
+
+ LICENSES/exceptions/Linux-syscall-note
+
+ Contains the Linux syscall exception as documented in the COPYING
+ file of the Linux kernel, which is used for UAPI header files.
+ e.g. /\* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note \*/::
+
+ LICENSES/exceptions/GCC-exception-2.0
+
+ Contains the GCC 'linking exception' which allows to link any binary
+ independent of its license against the compiled version of a file marked
+ with this exception. This is required for creating runnable executables
+ from source code which is not compatible with the GPL.
+
+ _`Exception Metatags`:
+
+ The following meta tags must be available in an exception file:
+
+ - SPDX-Exception-Identifier:
+
+ One exception identifier which can be used with SPDX license
+ identifiers.
+
+ - SPDX-URL:
+
+ The URL of the SPDX page which contains additional information related
+ to the exception.
+
+ - SPDX-Licenses:
+
+ A comma separated list of SPDX license identifiers for which the
+ exception can be used.
+
+ - Usage-Guidance:
+
+ Freeform text for usage advice. The text must be followed by correct
+ examples for the SPDX license identifiers as they should be put into
+ source files according to the `License identifier syntax`_ guidelines.
+
+ - Exception-Text:
+
+ All text after this tag is treated as the original exception text
+
+ File format examples::
+
+ SPDX-Exception-Identifier: Linux-syscall-note
+ SPDX-URL: https://spdx.org/licenses/Linux-syscall-note.html
+ SPDX-Licenses: GPL-2.0, GPL-2.0+, GPL-1.0+, LGPL-2.0, LGPL-2.0+, LGPL-2.1, LGPL-2.1+
+ Usage-Guidance:
+ This exception is used together with one of the above SPDX-Licenses
+ to mark user-space API (uapi) header files so they can be included
+ into non GPL compliant user-space application code.
+ To use this exception add it with the keyword WITH to one of the
+ identifiers in the SPDX-Licenses tag:
+ SPDX-License-Identifier: <SPDX-License> WITH Linux-syscall-note
+ Exception-Text:
+ Full exception text
+
+ ::
+
+ SPDX-Exception-Identifier: GCC-exception-2.0
+ SPDX-URL: https://spdx.org/licenses/GCC-exception-2.0.html
+ SPDX-Licenses: GPL-2.0, GPL-2.0+
+ Usage-Guidance:
+ The "GCC Runtime Library exception 2.0" is used together with one
+ of the above SPDX-Licenses for code imported from the GCC runtime
+ library.
+ To use this exception add it with the keyword WITH to one of the
+ identifiers in the SPDX-Licenses tag:
+ SPDX-License-Identifier: <SPDX-License> WITH GCC-exception-2.0
+ Exception-Text:
+ Full exception text
+
+
+All SPDX license identifiers and exceptions must have a corresponding file
+in the LICENSES subdirectories. This is required to allow tool
+verification (e.g. checkpatch.pl) and to have the licenses ready to read
+and extract right from the source, which is recommended by various FOSS
+organizations, e.g. the `FSFE REUSE initiative <https://reuse.software/>`_.
+
+_`MODULE_LICENSE`
+-----------------
+
+ Loadable kernel modules also require a MODULE_LICENSE() tag. This tag is
+ neither a replacement for proper source code license information
+ (SPDX-License-Identifier) nor in any way relevant for expressing or
+ determining the exact license under which the source code of the module
+ is provided.
+
+ The sole purpose of this tag is to provide sufficient information
+ whether the module is free software or proprietary for the kernel
+ module loader and for user space tools.
+
+ The valid license strings for MODULE_LICENSE() are:
+
+ ============================= =============================================
+ "GPL" Module is licensed under GPL version 2. This
+ does not express any distinction between
+ GPL-2.0-only or GPL-2.0-or-later. The exact
+ license information can only be determined
+ via the license information in the
+ corresponding source files.
+
+ "GPL v2" Same as "GPL". It exists for historic
+ reasons.
+
+ "GPL and additional rights" Historical variant of expressing that the
+ module source is dual licensed under a
+ GPL v2 variant and MIT license. Please do
+ not use in new code.
+
+ "Dual MIT/GPL" The correct way of expressing that the
+ module is dual licensed under a GPL v2
+ variant or MIT license choice.
+
+ "Dual BSD/GPL" The module is dual licensed under a GPL v2
+ variant or BSD license choice. The exact
+ variant of the BSD license can only be
+ determined via the license information
+ in the corresponding source files.
+
+ "Dual MPL/GPL" The module is dual licensed under a GPL v2
+ variant or Mozilla Public License (MPL)
+ choice. The exact variant of the MPL
+ license can only be determined via the
+ license information in the corresponding
+ source files.
+
+ "Proprietary" The module is under a proprietary license.
+ This string is solely for proprietary third
+ party modules and cannot be used for modules
+ which have their source code in the kernel
+ tree. Modules tagged that way are tainting
+ the kernel with the 'P' flag when loaded and
+ the kernel module loader refuses to link such
+ modules against symbols which are exported
+ with EXPORT_SYMBOL_GPL().
+ ============================= =============================================
+
+
+