DPKG-ARCHITECTUUser)Contributed Perl DocumentDPKG-ARCHITECTURE(E) NAME dpkg-architecture - set and determine the architecture for package building SYNOPSIS dpkg-architecture [options] [action] Valid options: -aDebian-Architecture -tGnu-System-Type -f Valid actions: -l, -qVariable-Name, -s, -u, -c Command DESCRIPTION dpkg-architecture does provide a facility to determine and set the build and host architecture for package building. OVERVIEW 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 envi- ronment which has all variables set to the determined value. Existing environment variables with the same name as used by the scripts are not overwritten, except if the -f force flag is present. This allows the user to override a value even when the call to dpkg-architecture is buried in some other script (for example dpkg-buildpackage). TERMS build machine The machine the package is build on. host machine The machine the package is build for. Debian Architecture The Debian archietcture string, which specifies the binary tree in the FTP archive. Examples: i386, sparc, hurd-i386. GNU System Type An architecture specification string consisting of two or three parts, cpu-system or cpu-vendor-system. Exam- ples: i386-linux, sparc-linux, i386-gnu. EXAMPLES dpkg-buildpackage accepts the -a option and passes it to dpkg-architecture. Other examples: CC=i386-gnu-gcc dpkg-architecture "-c" debian/rules build eval `dpkg-architecture "-u"` VARIABLES The following variables are set by dpkg-architecture: DEB_BUILD_ARCH The Debian architecture of the build machine. DEB_BUILD_GNU_TYPE The GNU system type of the build machine. DEB_BUILD_GNU_CPU The CPU part of DEB_BUILD_GNU_TYPE DEB_BUILD_GNU_SYSTEM The System part of DEB_BUILD_GNU_TYPE DEB_HOST_ARCH The Debian architecture of the host machine. DEB_HOST_GNU_TYPE The GNU system type of the host machine. DEB_HOST_GNU_CPU The CPU part of DEB_HOST_GNU_TYPE DEB_HOST_GNU_SYSTEM The System part of DEB_HOST_GNU_TYPE DEBIAN/RULES The environment variables set by dpkg-architecture are passed to debian/rules as make variables (see make docu- mentation). You can and should use them in the build pro- cess as needed. Here are some examples, which also show how you can improve the cross compilation support in your package: Instead: 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=$(H_ARCH) Instead: ARCH=`dpkg --print-architecture` ifeq ($(ARCH),alpha) ... endif please use: ARCH=$(DEB_HOST_ARCH) ifeq ($(ARCH),alpha) ... endif In general, calling dpkg in the rules file to get archi- tecture information is deprecated (until you want to pro- vide backward compatibility, see below). Especially the --print-architecture option is unreliable since we have Debian architectures which don't equal a processor name. BACKWARD COMPATIBILITY 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-archi- tecture) 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_SYS- TEM) DEB_HOST_ARCH=$(DEB_BUILD_ARCH) DEB_HOST_GNU_CPU=$(DEB_BUILD_GNU_CPU) DEB_HOST_GNU_SYS- TEM=$(DEB_BUILD_GNU_SYSTEM) DEB_HOST_GNU_TYPE=$(DEB_BUILD_GNU_TYPE) Put a subset of these lines at the top of your debian/rules file; these default values will be overwrit- ten 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 exam- ple, 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 tra- ditional 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 val- ues: DEB_BUILD_ARCH=`dpkg-architecture -qDEB_BUILD_ARCH` DEB_BUILD_GNU=`dpkg-architecture -qDEB_BUILD_GNU` etc. You get the idea. This way, you can ensure that the variables are never undeclared. Note that this breaks backwards compatibility with old build scripts, and you should only do that if source dependencies are implemented and declared accordingly. SEE ALSO dpkg-buildpackage dpkg-cross CONTACT If you have questions about the usage of the make vari- ables in your rules files, or about cross compilation sup- port in your packages, please email me. The address is Marcus Brinkmann <brinkmd@debian.org>. perl v5.6.1 2001-06-20 DPKG-ARCHITECTURE(E)