Valid options: -aDebian-Architecture -tGnu-System-Type -f
The build architecture is always determined by an external call to dpkg, and can not be set at the command line.
You can specify the host architecture by providing one or both of the options -a and -t. The default is determined by an external call to gcc, or the same as the build architecture if CC or gcc are both not available. One out of -a and -t is sufficient, the value of the other will be set to a usable default. Indeed, it is often better to only specify one, because dpkg-architecture will warn you if your choice doesn't match the default.
The default action is -l, which prints the environment variales, one each line, in the format VARIABLE=value. If you are only interested in the value of a single variable, you can use -q. If you specify -s, it will output an export command. This can be used to set the environment variables using eval. -u does return a similar command to unset all variables. -c does execute a command in an environment which has all variables set to the determined value.
The machine the package is build on.
The machine the package is build for.
The Debian archietcture string, which specifies the binary tree in the FTP archive. Examples: i386, sparc, hurd-i386.
GNU System Type
dpkg-buildpackage accepts the -a option and passes it to dpkg-architecture. Other examples:
CC=i386-gnu-gcc dpkg-architecture -c debian/rules build
The following variables are set by dpkg-architecture:
The Debian architecture of the build machine.
The GNU system type of the build machine.
The CPU part of DEB_BUILD_GNU_TYPE
The System part of DEB_BUILD_GNU_TYPE
The Debian architecture of the host machine.
The GNU system type of the host machine.
The CPU part of DEB_HOST_GNU_TYPE
The environment variables set by dpkg-architecture are passed to debian/rules as make variables (see make documentation). You can and should use them in the build process as needed. Here are some examples, which also show how you can improve the cross compilation support in your package:
ARCH=`dpkg --print-architecture` configure $( ARCH )-linux
please use the following:
B_ARCH=$( DEB_BUILD_GNU_TYPE ) H_ARCH=$( DEB_HOST_GNU_TYPE ) configure --build=$(B_ARCH) --host=$(H_ARCH)
ARCH=`dpkg --print-architecture` ifeq ($( ARCH ),alpha) ... endif
ARCH=$( DEB_HOST_ARCH ) ifeq ($( ARCH ),alpha) ... endif
When providing a new facility, it is always a good idea to stay compatible with old versions of the programs. Note that dpkg-architecture does not affect old debian/rules files, so the only thing to consider is using old building scripts with new debian/rules files. The following does the job:
DEB_BUILD_ARCH := $(shell dpkg --print-installation-architecture) DEB_BUILD_GNU_CPU := $(patsubst hurd-%,%,$( DEB_BUILD_ARCH )) ifeq ($(filter-out hurd-%,$( DEB_BUILD_ARCH )),) DEB_BUILD_GNU_SYSTEM := gnu else DEB_BUILD_GNU_SYSTEM := linux endif DEB_BUILD_GNU_TYPE=$( DEB_BUILD_GNU_CPU )-$( DEB_BUILD_GNU_SYSTEM )
DEB_HOST_ARCH=$( DEB_BUILD_ARCH ) DEB_HOST_GNU_CPU=$( DEB_BUILD_GNU_CPU ) DEB_HOST_GNU_SYSTEM=$( DEB_BUILD_GNU_SYSTEM ) DEB_HOST_GNU_TYPE=$( DEB_BUILD_GNU_TYPE )
Put a subset of these lines at the top of your debian/rules file; these default values will be overwritten if dpkg-architecture is used.
You don't need the full set. Choose a consistent set which contains the values you use in the rules file. For example, if you only need the host Debian architecture, `DEB_HOST_ARCH=`dpkg --print-installation-architecture` is sufficient (this is indeed the Debian architecture of the build machine, but remember that we are only trying to be backward compatible with native compilation).
You may not want to care about old build packages (for example, if you have sufficient source dependencies declared anyway). But you should at least support the traditional way to build packages by calling `debian/rules build' directly, without setting environment variables. To do this, use the -q option to query suitable default values: