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1 | Submitting Drivers For The Linux Kernel |
2 | --------------------------------------- | |
3 | ||
4 | This document is intended to explain how to submit device drivers to the | |
5 | various kernel trees. Note that if you are interested in video card drivers | |
6 | you should probably talk to XFree86 (http://www.xfree86.org/) and/or X.Org | |
7 | (http://x.org/) instead. | |
8 | ||
9 | Also read the Documentation/SubmittingPatches document. | |
10 | ||
11 | ||
12 | Allocating Device Numbers | |
13 | ------------------------- | |
14 | ||
15 | Major and minor numbers for block and character devices are allocated | |
16 | by the Linux assigned name and number authority (currently better | |
17 | known as H Peter Anvin). The site is http://www.lanana.org/. This | |
18 | also deals with allocating numbers for devices that are not going to | |
19 | be submitted to the mainstream kernel. | |
20 | ||
21 | If you don't use assigned numbers then when you device is submitted it will | |
22 | get given an assigned number even if that is different from values you may | |
23 | have shipped to customers before. | |
24 | ||
25 | Who To Submit Drivers To | |
26 | ------------------------ | |
27 | ||
28 | Linux 2.0: | |
29 | No new drivers are accepted for this kernel tree | |
30 | ||
31 | Linux 2.2: | |
32 | If the code area has a general maintainer then please submit it to | |
33 | the maintainer listed in MAINTAINERS in the kernel file. If the | |
34 | maintainer does not respond or you cannot find the appropriate | |
35 | maintainer then please contact Alan Cox <alan@lxorguk.ukuu.org.uk> | |
36 | ||
37 | Linux 2.4: | |
38 | The same rules apply as 2.2. The final contact point for Linux 2.4 | |
39 | submissions is Marcelo Tosatti <marcelo.tosatti@cyclades.com>. | |
40 | ||
41 | Linux 2.6: | |
42 | The same rules apply as 2.4 except that you should follow linux-kernel | |
43 | to track changes in API's. The final contact point for Linux 2.6 | |
44 | submissions is Andrew Morton <akpm@osdl.org>. | |
45 | ||
46 | What Criteria Determine Acceptance | |
47 | ---------------------------------- | |
48 | ||
49 | Licensing: The code must be released to us under the | |
50 | GNU General Public License. We don't insist on any kind | |
51 | of exclusively GPL licensing, and if you wish the driver | |
52 | to be useful to other communities such as BSD you may well | |
53 | wish to release under multiple licenses. | |
54 | ||
55 | Copyright: The copyright owner must agree to use of GPL. | |
56 | It's best if the submitter and copyright owner | |
57 | are the same person/entity. If not, the name of | |
58 | the person/entity authorizing use of GPL should be | |
59 | listed in case it's necessary to verify the will of | |
60 | the copright owner. | |
61 | ||
62 | Interfaces: If your driver uses existing interfaces and behaves like | |
63 | other drivers in the same class it will be much more likely | |
64 | to be accepted than if it invents gratuitous new ones. | |
65 | If you need to implement a common API over Linux and NT | |
66 | drivers do it in userspace. | |
67 | ||
68 | Code: Please use the Linux style of code formatting as documented | |
69 | in Documentation/CodingStyle. If you have sections of code | |
70 | that need to be in other formats, for example because they | |
71 | are shared with a windows driver kit and you want to | |
72 | maintain them just once separate them out nicely and note | |
73 | this fact. | |
74 | ||
75 | Portability: Pointers are not always 32bits, not all computers are little | |
76 | endian, people do not all have floating point and you | |
77 | shouldn't use inline x86 assembler in your driver without | |
78 | careful thought. Pure x86 drivers generally are not popular. | |
79 | If you only have x86 hardware it is hard to test portability | |
80 | but it is easy to make sure the code can easily be made | |
81 | portable. | |
82 | ||
83 | Clarity: It helps if anyone can see how to fix the driver. It helps | |
84 | you because you get patches not bug reports. If you submit a | |
85 | driver that intentionally obfuscates how the hardware works | |
86 | it will go in the bitbucket. | |
87 | ||
88 | Control: In general if there is active maintainance of a driver by | |
89 | the author then patches will be redirected to them unless | |
90 | they are totally obvious and without need of checking. | |
91 | If you want to be the contact and update point for the | |
92 | driver it is a good idea to state this in the comments, | |
93 | and include an entry in MAINTAINERS for your driver. | |
94 | ||
95 | What Criteria Do Not Determine Acceptance | |
96 | ----------------------------------------- | |
97 | ||
98 | Vendor: Being the hardware vendor and maintaining the driver is | |
99 | often a good thing. If there is a stable working driver from | |
100 | other people already in the tree don't expect 'we are the | |
101 | vendor' to get your driver chosen. Ideally work with the | |
102 | existing driver author to build a single perfect driver. | |
103 | ||
104 | Author: It doesn't matter if a large Linux company wrote the driver, | |
105 | or you did. Nobody has any special access to the kernel | |
106 | tree. Anyone who tells you otherwise isn't telling the | |
107 | whole story. | |
108 | ||
109 | ||
110 | Resources | |
111 | --------- | |
112 | ||
113 | Linux kernel master tree: | |
114 | ftp.??.kernel.org:/pub/linux/kernel/... | |
115 | ?? == your country code, such as "us", "uk", "fr", etc. | |
116 | ||
117 | Linux kernel mailing list: | |
118 | linux-kernel@vger.kernel.org | |
119 | [mail majordomo@vger.kernel.org to subscribe] | |
120 | ||
121 | Linux Device Drivers, Third Edition (covers 2.6.10): | |
122 | http://lwn.net/Kernel/LDD3/ (free version) | |
123 | ||
124 | Kernel traffic: | |
125 | Weekly summary of kernel list activity (much easier to read) | |
126 | http://www.kerneltraffic.org/kernel-traffic/ | |
127 | ||
128 | LWN.net: | |
129 | Weekly summary of kernel development activity - http://lwn.net/ | |
130 | 2.6 API changes: | |
131 | http://lwn.net/Articles/2.6-kernel-api/ | |
132 | Porting drivers from prior kernels to 2.6: | |
133 | http://lwn.net/Articles/driver-porting/ | |
134 | ||
135 | KernelTrap: | |
136 | Occasional Linux kernel articles and developer interviews | |
137 | http://kerneltrap.org/ | |
138 | ||
139 | KernelNewbies: | |
140 | Documentation and assistance for new kernel programmers | |
141 | http://kernelnewbies.org/ | |
142 | ||
143 | Linux USB project: | |
144 | http://sourceforge.net/projects/linux-usb/ | |
145 |