OpenWrt之package: Using Dependencies

OpenWrt之package: Using Dependencies

---

foreword

In this article, I translated from the OpenWrt document, and I will talk about the analysis of DEPENDS, @, &, there will inevitably be some problems. Welcome to point out that students with English foundation can go straight to the official|| ()

https://openwrt.org/docs/guide-developer/dependencies

https://openwrt.org/docs/guide-developer/packages

---

Overview/ Topic

A package Makefile includes the following sections:

define Package/tcpdump/default
  SECTION:=net
  CATEGORY:=Network
  DEPENDS:=+libpcap
  TITLE:=Network monitoring and data acquisition tool
  URL:=http://www.tcpdump.org/
endef

This article will describe what DEPENDS:=+libpcapthe row should look like

---

Dependency types / Dependency types

• Not selectable unless libpcapselectedtcpdump

DEPENDS:=libpcap

• If tcpdumpselected, libpcapwill also be selected

DEPENDS:=+libpcap

• If tcpdumpit is selected, arpd也会被选中. libpcapIt can be selected at this time, otherwise it cannot be selected.

DEPENDS:=+PACKAGE_arpd:libpcap

• BUSYBOXHOSTNAMEselect if not innet-tools-hostname

DEPENDS:=+!BUSYBOX_CONFIG_HOSTNAME:net-tools-hostname

• This option must exist USB_SUPPORT(defined), otherwise you will not see tcpdumpthis option

DEPENDS:=@USB_SUPPORT

• If tcpdumpselected, KERNEL_DEBUG_FSrelated items (including selected) will be automatically configured.

DEPENDS:=+@KERNEL_DEBUG_FS

Note: opkg installIt will not check KERNEL_DEBUG_FSwhether it is installed when using

• If net-tools-hostnameit is not selected, BUSYBOX_CONFIG_HOSTNAMErelated items will be automatically configured (including selected).

DEPENDS:=+@!PACKAGE_net-tools-hostname:BUSYBOX_CONFIG_HOSTNAME

---

Special Instructions / Special Notes

• You can Makefiledefine one that OpenWrt does not have Package, and DEPENDScall it in

define Package/package-name/config
    ...config stuff
endef

Include the following commands:

Order	meaning
select package	If tcpdumpchecked, packageit will also be checked.
select package if packageb	If packagebselected, packagewill also be selected
select package if SYMBOL	Not optional unless CONFIG_SYMBOLdefinedpackage
depends packageb	tcpdumpDepends on packageb, not packagebvisible unless selectedtcpdump
depends packageb if packagec	If packagecselected, tcpdumpwill depend onpackageb
select SYMBOL	If tcpdumpchecked, set to CONFIG_SYMBOL=y.
select SYMBOL if packageb	If packagebselected, select SYMBOLthe action to perform
select SYMBOL if SYMBOL2	If SYMBOL2defined, select SYMBOLthe action to perform

It should be noted that when Package/foo/configusing select bar, compile will be selected bar, but when using opkg install foo, there is no need to ensure foowhether it is installed

---

Warnings/Caveats

Packages and package dependencies cannot depend on each other ( Package Adepend on Package B, Package Bdepend on Package A), this situation is not allowed, if this kind of circular dependency is caused, make menuconfigother problems will occur in time.

---

Using boolean operators

• DEPENDS:@SYMBOLand DEPENDS:@SYMBOL:packagesyntactically support the bool operator operation of if, including: !, &&,||

• DEPENDS:+SYMBOL:packageThe syntax has restrictions on the operation of the bool operator, which !can only be used for the entire condition. 括号It is only for readability, and it has no effect. &&The priority is higher than that ||. So +(YYY||FOO&&BAR):packageif when YYYis selected or FOOboth BARare selected, packageit can be selected.

• +YYY||(FOO&&BAR):packageFor readability, it could be better

• But +(YYY||FOO)&&BAR:packagethis parenthesis does not change the priority, 括号it is just for readability and has no effect.

---

Afterword

The translation is still relatively weak, I don’t know if I can understand it, at least I understand it myself.

Welcome to pay attention to the WeChat public account: NueXiniShare

Enjoy it ~