diff options
Diffstat (limited to 'documentation/ref-manual/eclipse/html/poky-ref-manual/ref-features-backfill.html')
-rw-r--r-- | documentation/ref-manual/eclipse/html/poky-ref-manual/ref-features-backfill.html | 88 |
1 files changed, 0 insertions, 88 deletions
diff --git a/documentation/ref-manual/eclipse/html/poky-ref-manual/ref-features-backfill.html b/documentation/ref-manual/eclipse/html/poky-ref-manual/ref-features-backfill.html deleted file mode 100644 index 0ad90dfd70..0000000000 --- a/documentation/ref-manual/eclipse/html/poky-ref-manual/ref-features-backfill.html +++ /dev/null | |||
@@ -1,88 +0,0 @@ | |||
1 | <html> | ||
2 | <head> | ||
3 | <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> | ||
4 | <title>9.4. Feature Backfilling</title> | ||
5 | <link rel="stylesheet" type="text/css" href="../book.css"> | ||
6 | <meta name="generator" content="DocBook XSL Stylesheets V1.76.1"> | ||
7 | <link rel="home" href="index.html" title="The Yocto Project Reference Manual"> | ||
8 | <link rel="up" href="ref-features.html" title="Chapter 9. Reference: Features"> | ||
9 | <link rel="prev" href="ref-features-image.html" title="9.3. Images"> | ||
10 | <link rel="next" href="ref-variables-glos.html" title="Chapter 10. Variables Glossary"> | ||
11 | </head> | ||
12 | <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="section" title="9.4. Feature Backfilling"> | ||
13 | <div class="titlepage"><div><div><h2 class="title" style="clear: both"> | ||
14 | <a name="ref-features-backfill"></a>9.4. Feature Backfilling</h2></div></div></div> | ||
15 | <p> | ||
16 | Sometimes it is necessary in the OpenEmbedded build system to extend | ||
17 | <a class="link" href="ref-variables-glos.html#var-MACHINE_FEATURES" title="MACHINE_FEATURES"><code class="filename">MACHINE_FEATURES</code></a> | ||
18 | or <a class="link" href="ref-variables-glos.html#var-DISTRO_FEATURES" title="DISTRO_FEATURES"><code class="filename">DISTRO_FEATURES</code></a> | ||
19 | to control functionality that was previously enabled and not able | ||
20 | to be disabled. | ||
21 | For these cases, we need to add an | ||
22 | additional feature item to appear in one of these variables, | ||
23 | but we do not want to force developers who have existing values | ||
24 | of the variables in their configuration to add the new feature | ||
25 | in order to retain the same overall level of functionality. | ||
26 | Thus, the OpenEmbedded build system has a mechanism to | ||
27 | automatically "backfill" these added features into existing | ||
28 | distro or machine configurations. | ||
29 | You can see the list of features for which this is done by | ||
30 | finding the | ||
31 | <a class="link" href="ref-variables-glos.html#var-DISTRO_FEATURES_BACKFILL" title="DISTRO_FEATURES_BACKFILL"><code class="filename">DISTRO_FEATURES_BACKFILL</code></a> | ||
32 | and <a class="link" href="ref-variables-glos.html#var-MACHINE_FEATURES_BACKFILL" title="MACHINE_FEATURES_BACKFILL"><code class="filename">MACHINE_FEATURES_BACKFILL</code></a> | ||
33 | variables in the <code class="filename">meta/conf/bitbake.conf</code> file. | ||
34 | </p> | ||
35 | <p> | ||
36 | Because such features are backfilled by default into all | ||
37 | configurations as described in the previous paragraph, developers | ||
38 | who wish to disable the new features need to be able to selectively | ||
39 | prevent the backfilling from occurring. | ||
40 | They can do this by adding the undesired feature or features to the | ||
41 | <a class="link" href="ref-variables-glos.html#var-DISTRO_FEATURES_BACKFILL_CONSIDERED" title="DISTRO_FEATURES_BACKFILL_CONSIDERED"><code class="filename">DISTRO_FEATURES_BACKFILL_CONSIDERED</code></a> | ||
42 | or <a class="link" href="ref-variables-glos.html#var-MACHINE_FEATURES_BACKFILL_CONSIDERED" title="MACHINE_FEATURES_BACKFILL_CONSIDERED"><code class="filename">MACHINE_FEATURES_BACKFILL_CONSIDERED</code></a> | ||
43 | variables for distro features and machine features respectively. | ||
44 | </p> | ||
45 | <p> | ||
46 | Here are two examples to help illustrate feature backfilling: | ||
47 | </p> | ||
48 | <div class="itemizedlist"><ul class="itemizedlist" type="disc"> | ||
49 | <li class="listitem"><p><span class="emphasis"><em>The "pulseaudio" distro feature option</em></span>: | ||
50 | Previously, PulseAudio support was enabled within the Qt and | ||
51 | GStreamer frameworks. | ||
52 | Because of this, the feature is backfilled and thus | ||
53 | enabled for all distros through the | ||
54 | <code class="filename">DISTRO_FEATURES_BACKFILL</code> | ||
55 | variable in the <code class="filename">meta/conf/bitbake.conf</code> file. | ||
56 | However, your distro needs to disable the feature. | ||
57 | You can disable the feature without affecting | ||
58 | other existing distro configurations that need PulseAudio support | ||
59 | by adding "pulseaudio" to | ||
60 | <code class="filename">DISTRO_FEATURES_BACKFILL_CONSIDERED</code> | ||
61 | in your distro's <code class="filename">.conf</code> file. | ||
62 | Adding the feature to this variable when it also | ||
63 | exists in the <code class="filename">DISTRO_FEATURES_BACKFILL</code> | ||
64 | variable prevents the build system from adding the feature to | ||
65 | your configuration's <code class="filename">DISTRO_FEATURES</code>, effectively disabling | ||
66 | the feature for that particular distro.</p></li> | ||
67 | <li class="listitem"><p><span class="emphasis"><em>The "rtc" machine feature option</em></span>: | ||
68 | Previously, real time clock (RTC) support was enabled for all | ||
69 | target devices. | ||
70 | Because of this, the feature is backfilled and thus enabled | ||
71 | for all machines through the <code class="filename">MACHINE_FEATURES_BACKFILL</code> | ||
72 | variable in the <code class="filename">meta/conf/bitbake.conf</code> file. | ||
73 | However, your target device does not have this capability. | ||
74 | You can disable RTC support for your device without | ||
75 | affecting other machines that need RTC support | ||
76 | by adding the feature to your machine's | ||
77 | <code class="filename">MACHINE_FEATURES_BACKFILL_CONSIDERED</code> | ||
78 | list in the machine's <code class="filename">.conf</code> file. | ||
79 | Adding the feature to this variable when it also | ||
80 | exists in the <code class="filename">MACHINE_FEATURES_BACKFILL</code> | ||
81 | variable prevents the build system from adding the feature to | ||
82 | your configuration's <code class="filename">MACHINE_FEATURES</code>, effectively | ||
83 | disabling RTC support for that particular machine.</p></li> | ||
84 | </ul></div> | ||
85 | <p> | ||
86 | </p> | ||
87 | </div></body> | ||
88 | </html> | ||