Libosmocore » History » Version 2
laforge, 02/19/2016 10:49 PM
add section on libosmocore development cycle
1 | 1 | laforge | [[PageOutline]] |
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2 | = libosmocore = |
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3 | |||
4 | libosmocore is a library with various utility functions that were originally developed as part of |
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5 | the [wiki:OpenBSC] project, but which are of a more generic nature and thus useful to (at least) |
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6 | other programs that we develop in the sphere of Open Source mobile communications. |
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7 | |||
8 | There is no clear scope of it. We simply move all shared code between [wiki:OsmocomBB] and [wiki:OpenBSC] |
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9 | in this library to avoid code duplication. |
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10 | |||
11 | == Obtaining it == |
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12 | |||
13 | When you download and build [wiki:OsmocomBB], then libosmocore is automatically part of the package, |
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14 | no special action is required. |
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15 | |||
16 | If you want to obtain a standalone version of libosmocore, you can use the following git URL: |
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17 | {{{git clone git://git.osmocom.org/libosmocore.git}}} |
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18 | |||
19 | == Licensing == |
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20 | |||
21 | This library is GPL licensed, as the code is taken from the similarly GPL-licensed OpenBSC codebase. |
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22 | |||
23 | This means you '''cannot use this library from non-GPL licensed code without infringing copyright! |
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24 | |||
25 | == Features == |
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26 | |||
27 | === Select loop abstraction === |
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28 | |||
29 | This is implemented in select.[ch] and enables you to build complex asynchronous/non-blocking I/O |
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30 | programs in a single thread. |
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31 | |||
32 | === Message buffer handling === |
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33 | |||
34 | Inspired by the Linux kernel {{{struct sk_buff}}}, this is our message buffer {{{struct msgb}}} |
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35 | implementation. It provides handling of packet buffers, putting them in queues, prepending |
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36 | and appending data to it, etc. |
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37 | |||
38 | === Bitvector === |
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39 | |||
40 | A convenient set of routines to deal with bit-vectors in C. This was originally written |
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41 | for rest-octet parsing. |
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42 | |||
43 | === TLV handling === |
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44 | |||
45 | The GSM Layer3 and above are full of TV / TLV / TL16V and other data fields. Our implementation |
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46 | provides parser and generator functions, tightly coupled to {{{struct msgb}}} |
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47 | |||
48 | === Timers === |
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49 | |||
50 | Provides a timer core where you can register timers with a callback function. The function |
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51 | is called when the timer expires. |
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52 | |||
53 | === Comp128v1 === |
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54 | |||
55 | A Comp128v1 implementation by Sylvain Munaut is included. |
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56 | |||
57 | === Talloc memory allocator === |
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58 | |||
59 | The talloc memory allocator from the Samba project. |
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60 | 2 | laforge | |
61 | == Development Cycle == |
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62 | |||
63 | As we are still developing the GSM protocol stacks on the network side (OpenBSC) and phone side (OsmocomBB), |
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64 | every so often there is a need to add some new code to libosmocore. Even worse, we sometimes need to break |
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65 | the API and ABI of the library. |
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66 | |||
67 | However, by keeping libosmocore in a separate git repository, we run into one problem: Checking out an old |
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68 | version of e.g. OpenBSC or OsmocomBB will result in failed builds, as we don't remember which old version |
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69 | of libosmocore was required. This makes debugging and things like git bisect very hard to impossible. |
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70 | |||
71 | In order to solve this problem, we use [http://github.com/apenwarr/git-subtree git-subtree] to import the |
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72 | full libosmocore.git repository into OsmocomBB. |
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73 | |||
74 | This way, we ensure that there is always a compatible version of libosmocore inside the tree if we check out |
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75 | old OsmocomBB versions from git. |
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76 | |||
77 | === Making changes to libosmocore === |
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78 | |||
79 | '''NEVER COMMIT CHANGES DIRECTLY TO osmocom-bb.git:src/shared/libosmocore''' |
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80 | |||
81 | Instead, use the following process: |
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82 | 1. make your changes to your local copy of libosmocore |
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83 | 1. test them together with OsmocomBB and OpenBSC |
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84 | 1. test if libosmocore still builds for both host and target (ARM) |
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85 | 1. create a ''diff'' of your local libosmocore changes |
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86 | 1. apply that diff to the libosmocore.git repository |
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87 | 1. use the script in osmocom-bb.git/src/shared/update-libosmocore.sh (uses git-subtree) to import your changes from libosmocore.git |
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88 | 1. test + commit your OsmocomBB changes that depend on the newly introduced code to libosmocore |
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89 | |||
90 | It is important that the steps are followed in the order state above to ensure consistency of our repositories |