From 111f0678eecb63f8f44a5128bc3bfc46942231a7 Mon Sep 17 00:00:00 2001 From: Scott Rifenbark Date: Thu, 2 Dec 2010 14:21:58 -0800 Subject: documentation/poky-ref-manual: General edits up the Parsing section. Signed-off-by: Scott Rifenbark --- documentation/poky-ref-manual/ref-bitbake.xml | 82 +++++++++++++-------------- 1 file changed, 41 insertions(+), 41 deletions(-) (limited to 'documentation/poky-ref-manual') diff --git a/documentation/poky-ref-manual/ref-bitbake.xml b/documentation/poky-ref-manual/ref-bitbake.xml index 6221a963d8..9554c11388 100644 --- a/documentation/poky-ref-manual/ref-bitbake.xml +++ b/documentation/poky-ref-manual/ref-bitbake.xml @@ -6,32 +6,34 @@ Reference: BitBake - BitBake is a program written in Python that interprets the metadata - that makes up Poky. At some point, people wonder what actually happens - when you type bitbake poky-image-sato. This section - aims to give an overview of what happens behind the scenes from a - BitBake perspective. + BitBake is a program written in Python that interprets the metadata that makes up Poky. + At some point, people wonder what actually happens when you enter: + + $ bitbake poky-image-sato + - + - It is worth noting that BitBake aims to be a generic "task" executor - capable of handling complex dependency relationships. As such it has no - real knowledge of what the tasks it is executing actually do. It just - considers a list of tasks with dependencies and handles metadata - consisting of variables in a certain format which get passed to the - tasks. + This appendix provides an overview of what happens behind the scenes from BitBake's perspective. + + BitBake strives to be a generic "task" executor that is capable of handling complex dependency relationships. + As such, it has no real knowledge of what the tasks being executed actually do. + BitBake just considers a list of tasks with dependencies and handles metadata + that consists of variables in a certain format that get passed to the tasks. + +
Parsing The first thing BitBake does is work out its configuration by looking for a file called bitbake.conf. - BitBake searches through the BBPATH environment + BitBake examines the BBPATH environment variable looking for a conf/ - directory containing a bitbake.conf file and - adds the first bitbake.conf file found in + directory that contains a bitbake.conf file. + BitBake adds the first bitbake.conf file found in BBPATH (similar to the PATH environment variable). For Poky, bitbake.conf is found in meta/conf/. @@ -42,32 +44,32 @@ files to include from a conf/ directory below the directories listed in BBPATH. In general the most important configuration file from a user's perspective - is local.conf, which contains a users customized - settings for Poky. Other notable configuration files are the distribution + is local.conf, which contains a user's customized + settings for Poky. + Other notable configuration files are the distribution configuration file (set by the DISTRO variable) and the machine configuration file (set by the MACHINE - variable). The - DISTRO and - MACHINE environment variables are both usually set in - the local.conf file. Valid distribution + variable). + The DISTRO and MACHINE environment variables are both usually set in + the local.conf file. + Valid distribution configuration files are available in the meta/conf/distro/ directory and valid machine configuration files in the meta/conf/machine/ - directory. Within the - meta/conf/machine/include/ directory are various - tune-*.inc configuration files which provide common - "tuning" settings specific to and shared between particular - architectures and machines. + directory. + Within the meta/conf/machine/include/ + directory are various tune-*.inc configuration files that provide common + "tuning" settings specific to and shared between particular architectures and machines. - After the parsing of the configuration files some standard classes - are included. In particular, base.bbclass is - always included, as will any other classes - specified in the configuration using the INHERIT - variable. Class files are searched for in a classes subdirectory + After the parsing of the configuration files some standard classes are included. + The base.bbclass file is always included. + Other classes that are specified in the configuration using the + INHERIT + variable are also inculded. + Class files are searched for in a classes subdirectory under the paths in BBPATH in the same way as configuration files. @@ -77,21 +79,19 @@ variable BBFILES is set, usually in local.conf, and defines the list of places to search for - .bb files. By - default this specifies the meta/packages/ + .bb files. + By default this specifies the meta/packages/ directory within Poky, but other directories such as meta-extras/ can be included - too. Adding extra content to - BBFILES is best - acheived through the use of BitBake + too. + Adding extra content to BBFILES is best acheived through the use of BitBake "layers". - BitBake parses each .bb file in - BBFILES and - stores the values of various variables. In summary, for each - .bb + BitBake parses each .bb file in BBFILES and + stores the values of various variables. + In summary, for each .bb file the configuration + base class of variables are set, followed by the data in the .bb file itself, followed by any inherit commands that -- cgit v1.2.3-54-g00ecf