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author | Ed Tanous <ed.tanous@intel.com> | 2019-05-29 19:22:39 +0300 |
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committer | Ed Tanous <ed.tanous@intel.com> | 2019-05-29 19:22:39 +0300 |
commit | 5364646cb66fa75cdcbf148e039e0383cda94f2a (patch) | |
tree | 78b1711f353235e812435be90e124eab4037294e /poky/bitbake/doc/bitbake-user-manual/bitbake-user-manual-metadata.xml | |
parent | 816d793003e93c1e5eec0a2e90fbd8b9dde9f7a5 (diff) | |
parent | 7b595c2f82912a170774e84e5bb81d1b6030bf6b (diff) | |
download | openbmc-5364646cb66fa75cdcbf148e039e0383cda94f2a.tar.xz |
Merge branch 'master' of ssh://git-amr-1.devtools.intel.com:29418/openbmc-openbmc into intel
Diffstat (limited to 'poky/bitbake/doc/bitbake-user-manual/bitbake-user-manual-metadata.xml')
-rw-r--r-- | poky/bitbake/doc/bitbake-user-manual/bitbake-user-manual-metadata.xml | 72 |
1 files changed, 72 insertions, 0 deletions
diff --git a/poky/bitbake/doc/bitbake-user-manual/bitbake-user-manual-metadata.xml b/poky/bitbake/doc/bitbake-user-manual/bitbake-user-manual-metadata.xml index 199ab2309..a125ad332 100644 --- a/poky/bitbake/doc/bitbake-user-manual/bitbake-user-manual-metadata.xml +++ b/poky/bitbake/doc/bitbake-user-manual/bitbake-user-manual-metadata.xml @@ -61,6 +61,78 @@ </para> </section> + <section id='modifying-existing-variables'> + <title>Modifying Existing Variables</title> + + <para> + Sometimes you need to modify existing variables. + Following are some cases where you might find you want to + modify an existing variable: + <itemizedlist> + <listitem><para> + Customize a recipe that uses the variable. + </para></listitem> + <listitem><para> + Change a variable's default value used in a + <filename>*.bbclass</filename> file. + </para></listitem> + <listitem><para> + Change the variable in a <filename>*.bbappend</filename> + file to override the variable in the original recipe. + </para></listitem> + <listitem><para> + Change the variable in a configuration file so that the + value overrides an existing configuration. + </para></listitem> + </itemizedlist> + </para> + + <para> + Changing a variable value can sometimes depend on how the + value was originally assigned and also on the desired + intent of the change. + In particular, when you append a value to a variable that + has a default value, the resulting value might not be what + you expect. + In this case, the value you provide might replace the value + rather than append to the default value. + </para> + + <para> + If after you have changed a variable's value and something + unexplained occurs, you can use BitBake to check the actual + value of the suspect variable. + You can make these checks for both configuration and recipe + level changes: + <itemizedlist> + <listitem><para> + For configuration changes, use the following: + <literallayout class='monospaced'> + $ bitbake -e + </literallayout> + This command displays variable values after the + configuration files (i.e. <filename>local.conf</filename>, + <filename>bblayers.conf</filename>, + <filename>bitbake.conf</filename> and so forth) have + been parsed. + <note> + Variables that are exported to the environment are + preceded by the string "export" in the command's + output. + </note> + </para></listitem> + <listitem><para> + For recipe changes, use the following: + <literallayout class='monospaced'> + $ bitbake <replaceable>recipe</replaceable> -e | grep VARIABLE=" + </literallayout> + This command checks to see if the variable actually + makes it into a specific recipe. + </para></listitem> + </itemizedlist> + </para> + </section> + <section id='line-joining'> <title>Line Joining</title> |