License Profile for Latest Linux Kernel (2.6.22.1)
Here are some stats reflecting the licensing profile of the latest kernel.org Linux kernel 2.6.22.1.
| V2 Only | Any Later Version | General Total | |
|---|---|---|---|
| Authors | 703 (46%) | 814 (53%) | 1517 |
| c Files | 6222 (66%) | 3133 (33%) | 9355 |
| h Files | 7187 (80%) | 1771 (19%) | 8958 |
| Explicit V2 Only | Any Later Version | Explicit Copyright Total | |
|---|---|---|---|
| Authors | 703 (46%) | 814 (53%) | 1517 |
| c Files | 4143 (56%) | 3133 (43%) | 7276 |
| h Files | 2791 (61%) | 1771 (38%) | 4562 |
| Note 1: | There are approximately 1517 authors and contributors listed as copyright holders in the “.c” files of the kernel. Of these, 703 contributors are associated uniquely with files that can be characterized as “V2 only”. These 703 contributors do not appear in files that allow “any later version” licensing. However, 814 contributors are associated with files that allow “any later version” licensing. This means that there are more kernel contributors associated with “GPLv2 or later” source code files: 53% of the author pool, including ironically Linus himself. |
|---|---|
| Note 2: | There are 9355 “.c” files of which 7276 have explicit copyright notices. Of these 3133 allow “any later version” licensing. 2079 “.c” files have no explicit copyright notice and therefore fall under the overall default kernel license (V2). Therefore, 43% (3133 out of 7276) of the kernel “.c” files that have explicit copyright notices also have flexible licensing. |
| Note 3: | There are 8958 “.h” files of which 4562 have explicit copyright notices. Of these 1771 allow “any later version” licensing. 4396 “.h” files have no explicit copyright notice and therefore fall under the overall kernel license (V2). This means that 38% (1771 out of 4562) of the kernel “.h” files that have explicit copyright notices also have flexible licensing. |
| Note 4: | “V2 Only” is the default license imposed on a source or header file if no copyright information is explicitly mentioned. It is also the license imposed on the whole kernel whose components are often otherwise licensed as “V2 or any later version”. Therefore, one could argue that the intent of many authors is being contravened by downgrading the range of choice of license for the work as a whole. |
| Note 5: | Counts of contributors are approximate since their copyright references had to be cleaned up due to variations in their syntax and presentation. For reference are two lists of authors derived from the kernel “.c” sources: v2 only contributors and any later version contributors. Since they are disjoint, the lists can be combined to form a complete picture of all the authors of the Linux kernel. |
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