A typical package Makefile will contain a section like:
define Package/tcpdump/default SECTION:=net CATEGORY:=Network DEPENDS:=+libpcap TITLE:=Network monitoring and data acquisition tool URL:=http://www.tcpdump.org/ endef
This page talks about what the DEPENDS:= line should look like.
would mean that tcpdump would not be shown as possible to be selected unless
libpcap were already selected
+packagethat means if the current package is selected, it will cause
packageto be selected. This is the case with
tcpdumpabove. It says that if
tcpdumpis selected, then select
+PACKAGE_packageb:packagec, it means that
packagecwill only get selected by the current package (e.g.
packagebis enabled. e.g.
would mean that if
tcpdump was selected, then if
arpd was also selected, select
Useful is the negation ! to only select a Package if it's not build into busybox
This means select net-tools-hostname only if hostname is not build into busybox. But don't try it the other way around, see the last case.
@SYMBOLthat means that CONFIG_SYMBOL must be defined by OpenWrt in order for the
packageto be available for selection. e.g
would mean that the package wouldn't even appear unless config symbol CONFIG_USB_SUPPORT was defined, for example by the package
+@SYMBOLthat means if the current package is selected, it will cause CONFIG_SYMBOL to be selected.
would mean that the if you select the package, it would automatically set the config symbol CONFIG_KERNEL_DEBUG_FS. Beware: This works while compiling your own image. If you install this package on a running box with opkg, this dependency is not checked!
Here we select the Symbol BUSYBOX_CONFIG_HOSTNAME if the package net-tools-hostname is not selected. The @ belongs to BUSYBOX_CONFIG_HOSTNAME. This works while compiling your own image, but the resulting ipkg depends on the unresolvable BUSYBOX_CONFIG_HOSTNAME, so your package cannot be installed later on a box with opkg.
As busybox can never be extended on a working box, always select an installable package when a busybox applet is not selected.
It is possible to do select and depend on packages outside the usual
DEPENDS definition. If, in the package
Makefile, you have a definition:
define Package/package-name/config ...config stuff endef
then you can include the following directives.
|select package||Selects a package if this package is selected|
|select package if packageb||Selects a package if packageb is selected as well as this package|
|select package if SYMBOL||Selects a package if CONFIG_SYMBOL is defined|
|depends packageb||This package depends on packageb (i.e. won't even show up, unless packageb is selected)|
|depends packageb if packagec||This package depends on packageb if packagec is selected|
|select SYMBOL||Sets a symbol to y if this package is selected (.e.g. select BUSYBOX_FEATURE_MKSWAP_UUID)|
|select SYMBOL if packageb||Like select SYMBOL but only if packageb is selected|
|select SYMBOL if SYMBOL2||Like select SYMBOL but only if SYMBOL2 is defined|
The author is not aware of the ability to do
Note that the
if directives may also include &&, ||, !, and uses parentheses () to use logical expression for AND (&&), OR (||) and NOT (!), and for order of operations ('()').
There is also a
default 'y' SYMBOL directive but the author is hazy on the details.
It is important to note that using
select bar in
Package/foo/config directives will select
bar for building, but it will not be included in the dependencies when
foo, nor will it guarantee that
bar will be built before
DEPENDS will take care of all that.
Dependencies MAY NOT be circular (i.e. Package A may not depend on Package B, which in turn depends on Package A). If a circular dependency is created (whether directly or through another package), strange
make menuconfig behaviour will be the result.
DEPENDS:@SYMBOL:package syntax have good support for boolean operators, including parentheses, negation (
- The support for operators in the
DEPENDS:+SYMBOL:package syntax is limited. Negation
! is only supported to negate the whole condition. Parentheses are ignored, so use them only for readability.
&& has a higher precedence than
+(YYY||FOO&&BAR):package will select package if
CONFIG_YYY is set or if both
CONFIG_BAR are set. You may use
+YYY||(FOO&&BAR):package for readability, but writing
+(YYY||FOO)&&BAR:package will not change the condition to select package if either YYY or FOO is selected and BAR is selected.
There may be bugs in the OpenWrt build system wrt to dependencies. If you can confirm that you have a dependency problem, please report a bug. The developers would appreciate the following information:
$ROOTDIR/tmp/.config-package.in(where $ROOTDIR is your OpenWrt source root dir)
NB Many apparent bugs are caused by circular dependencies. The OpenWrt build system doesn't like circular dependencies.