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Diffstat (limited to 'documentation/ref-manual/ref-variables.xml')
| -rw-r--r-- | documentation/ref-manual/ref-variables.xml | 28 |
1 files changed, 28 insertions, 0 deletions
diff --git a/documentation/ref-manual/ref-variables.xml b/documentation/ref-manual/ref-variables.xml index 1181d64576..4316ea5dc6 100644 --- a/documentation/ref-manual/ref-variables.xml +++ b/documentation/ref-manual/ref-variables.xml @@ -9951,6 +9951,34 @@ recipes-graphics/xorg-font/font-alias_1.0.3.bb:PR = "${INC_PR}.3" The <filename>PROVIDES</filename> statement results in the "libav" recipe also being known as "libpostproc". </para> + + <para> + In addition to providing recipes under alternate names, + the <filename>PROVIDES</filename> mechanism is also used + to implement virtual targets. + A virtual target is a name that corresponds to some + particular functionality (e.g. a Linux kernel). + Recipes that provide the functionality in question list the + virtual target in <filename>PROVIDES</filename>. + Recipes that depend on the functionality in question can + include the virtual target in + <link linkend='var-DEPENDS'><filename>DEPENDS</filename></link> + to leave the choice of provider open. + </para> + + <para> + Conventionally, virtual targets have names on the form + "virtual/function" (e.g. "virtual/kernel"). + The slash is simply part of the name and has no + syntactical significance. + </para> + + <para> + The + <link linkend='var-PREFERRED_PROVIDER'><filename>PREFERRED_PROVIDER</filename></link> + variable is used to select which particular recipe + provides a virtual target. + </para> </glossdef> </glossentry> |