diff options
| -rw-r--r-- | bitbake/doc/user-manual/user-manual-metadata.xml | 28 |
1 files changed, 24 insertions, 4 deletions
diff --git a/bitbake/doc/user-manual/user-manual-metadata.xml b/bitbake/doc/user-manual/user-manual-metadata.xml index 0ce2549daf..69d103dcac 100644 --- a/bitbake/doc/user-manual/user-manual-metadata.xml +++ b/bitbake/doc/user-manual/user-manual-metadata.xml | |||
| @@ -474,10 +474,24 @@ | |||
| 474 | </para> | 474 | </para> |
| 475 | </section> | 475 | </section> |
| 476 | 476 | ||
| 477 | <section> | 477 | <section id='tasks'> |
| 478 | <title>Tasks</title> | 478 | <title>Tasks</title> |
| 479 | <para><emphasis>NOTE:</emphasis> This is only supported in .bb and .bbclass files.</para> | 479 | |
| 480 | <para>In BitBake, each step that needs to be run for a given .bb is known as a task. There is a command <filename>addtask</filename> to add new tasks (must be a defined Python executable metadata and must start with <quote>do_</quote>) and describe intertask dependencies. | 480 | <note> |
| 481 | This is only supported in <filename>.bb</filename> | ||
| 482 | and <filename>.bbclass</filename> files. | ||
| 483 | </note> | ||
| 484 | |||
| 485 | <para> | ||
| 486 | A shell or Python function executable through the | ||
| 487 | <filename>exec_func</filename> can be promoted to become a task. | ||
| 488 | Tasks are the execution unit Bitbake uses and each step that | ||
| 489 | needs to be run for a given <filename>.bb</filename> is known as | ||
| 490 | a task. | ||
| 491 | There is an <filename>addtask</filename> command to add new tasks | ||
| 492 | and promote functions which by convention must start with “do_”. | ||
| 493 | The <filename>addtask</filename> command is also used to describe | ||
| 494 | intertask dependencies. | ||
| 481 | <literallayout class='monospaced'> | 495 | <literallayout class='monospaced'> |
| 482 | python do_printdate () { | 496 | python do_printdate () { |
| 483 | import time print | 497 | import time print |
| @@ -485,7 +499,13 @@ | |||
| 485 | } | 499 | } |
| 486 | addtask printdate after do_fetch before do_build | 500 | addtask printdate after do_fetch before do_build |
| 487 | </literallayout> | 501 | </literallayout> |
| 488 | This defines the necessary Python function and adds it as a task which is now a dependency of do_build, the default task. If anyone executes the do_build task, that will result in do_printdate being run first. | 502 | The above example defined a Python function, then adds |
| 503 | it as a task which is now a dependency of | ||
| 504 | <filename>do_build</filename>, the default task and states it | ||
| 505 | has to happen after <filename>do_fetch</filename>. | ||
| 506 | If anyone executes the <filename>do_build</filename> | ||
| 507 | task, that will result in <filename>do_printdate</filename> | ||
| 508 | being run first. | ||
| 489 | </para> | 509 | </para> |
| 490 | </section> | 510 | </section> |
| 491 | 511 | ||
