dpkg/scripts/dpkg-architecture.1

.rn '' }`
''' $RCSfile: dpkg-architecture.1,v $$Revision: 1.4 $$Date: 1999/09/27 01:37:25 $
'''
''' $Log: dpkg-architecture.1,v $
''' Revision 1.4  1999/09/27 01:37:25  wakkerma
''' Updated to dpkg 1.4.1.11
'''
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.rm #[ #] #H #V #F C
.SH "NAME"
dpkg-architecture \- set and determine the architecture for package building
.SH "SYNOPSIS"
dpkg-architecture [options] [action]
.PP
Valid options:
\fB\-a\fRDebian-Architecture
\fB\-t\fRGnu-System-Type
\fB\-f\fR
.PP
Valid actions:
\fB\-l\fR, \fB\-q\fRVariable-Name, \fB\-s\fR, \fB\-u\fR, \fB\-c\fR Command
.SH "DESCRIPTION"
dpkg-architecture does provide a facility to determine and set the build and
host architecture for package building.
.SH "OVERVIEW"
The build architecture is always determined by an external call to dpkg, and
can not be set at the command line.
.PP
You can specify the host architecture by providing one or both of the options \fB\-a\fR
and \fB\-t\fR. 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 \fB\-a\fR and \fB\-t\fR
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.
.PP
The default action is \fB\-l\fR, 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 \fB\-q\fR. If you specify \fB\-s\fR, it will output an export
command. This can be used to set the environment variables using eval. \fB\-u\fR
does return a similar command to unset all variables. \fB\-c\fR does execute a
command in an environment which has all variables set to the determined
value.
.PP
Existing environment variables with the same name as used by the scripts are
not overwritten, except if the \fB\-f\fR 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). The \fB\-q\fR query option
implies \fB\-f\fR, and is therefore not affected by existing environment settings.
.SH "TERMS"
.Ip "build machine" 4
The machine the package is build on.
.Ip "host machine" 4
The machine the package is build for.
.Ip "Debian Architecture" 4
The Debian archietcture string, which specifies the binary tree in the \s-1FTP\s0
archive. Examples: i386, sparc, hurd-i386.
.Ip "\s-1GNU\s0 System Type" 4
An architecture specification string consisting of two or three parts,
cpu-system or cpu-vendor-system. Examples: i386-linux, sparc-linux, i386-gnu.
.SH "EXAMPLES"
dpkg-buildpackage accepts the \fB\-a\fR option and passes it to dpkg-architecture.
Other examples:
.PP
CC=i386-gnu-gcc dpkg-architecture \f(CW-c\fR debian/rules build
.PP
eval `dpkg-architecture \f(CW-u\fR`
.SH "VARIABLES"
The following variables are set by dpkg-architecture:
.Ip "\s-1DEB_BUILD_ARCH\s0" 4
The Debian architecture of the build machine.
.Ip "\s-1DEB_BUILD_GNU_TYPE\s0" 4
The \s-1GNU\s0 system type of the build machine.
.Ip "\s-1DEB_BUILD_GNU_CPU\s0" 4
The \s-1CPU\s0 part of \s-1DEB_BUILD_GNU_TYPE\s0
.Ip "\s-1DEB_BUILD_GNU_SYSTEM\s0" 4
The System part of \s-1DEB_BUILD_GNU_TYPE\s0
.Ip "\s-1DEB_HOST_ARCH\s0" 4
The Debian architecture of the host machine.
.Ip "\s-1DEB_HOST_GNU_TYPE\s0" 4
The \s-1GNU\s0 system type of the host machine.
.Ip "\s-1DEB_HOST_GNU_CPU\s0" 4
The \s-1CPU\s0 part of \s-1DEB_HOST_GNU_TYPE\s0
.Ip "\s-1DEB_HOST_GNU_SYSTEM\s0" 4
The System part of \s-1DEB_HOST_GNU_TYPE\s0
.SH "DEBIAN/RULES"
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:
.PP
Instead:
.PP
ARCH=`dpkg --print-architecture`
configure $(ARCH)\-linux
.PP
please use the following:
.PP
B_ARCH=$(DEB_BUILD_GNU_TYPE)
H_ARCH=$(DEB_HOST_GNU_TYPE)
configure --build=$(B_ARCH) --host=$(H_ARCH)
.PP
Instead:
.PP
ARCH=`dpkg --print-architecture`
ifeq ($(ARCH),alpha)
  ...
endif
.PP
please use:
.PP
ARCH=$(DEB_HOST_ARCH)
ifeq ($(ARCH),alpha)
  ...
endif
.PP
In general, calling dpkg in the rules file to get architecture information
is deprecated (until you want to provide backward compatibility, see below).
Especially the --print-architecture option is unreliable since we have
Debian architectures which don't equal a processor name.
.SH "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:
.PP
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)
.PP
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)
.PP
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.
.PP
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).
.PP
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\*(R' directly, without setting environment variables. To do this, use the
\fB\-q\fR option to query suitable default values:
.PP
DEB_BUILD_ARCH=`dpkg-architecture \-qDEB_BUILD_ARCH`
DEB_BUILD_GNU=`dpkg-architecture \-qDEB_BUILD_GNU`
.PP
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.
.SH "SEE ALSO"
dpkg-buildpackage
dpkg-cross
.SH "CONTACT"
If you have questions about the usage of the make variables in your rules
files, or about cross compilation support in your packages, please email me.
The addresse is Marcus Brinkmann <brinkmd@debian.org>.

.rn }` ''
.IX Title "DPKG-ARCHITECTURE 1"
.IX Name "dpkg-architecture - set and determine the architecture for package building"

.IX Header "NAME"

.IX Header "SYNOPSIS"

.IX Header "DESCRIPTION"

.IX Header "OVERVIEW"

.IX Header "TERMS"

.IX Item "build machine"

.IX Item "host machine"

.IX Item "Debian Architecture"

.IX Item "\s-1GNU\s0 System Type"

.IX Header "EXAMPLES"

.IX Header "VARIABLES"

.IX Item "\s-1DEB_BUILD_ARCH\s0"

.IX Item "\s-1DEB_BUILD_GNU_TYPE\s0"

.IX Item "\s-1DEB_BUILD_GNU_CPU\s0"

.IX Item "\s-1DEB_BUILD_GNU_SYSTEM\s0"

.IX Item "\s-1DEB_HOST_ARCH\s0"

.IX Item "\s-1DEB_HOST_GNU_TYPE\s0"

.IX Item "\s-1DEB_HOST_GNU_CPU\s0"

.IX Item "\s-1DEB_HOST_GNU_SYSTEM\s0"

.IX Header "DEBIAN/RULES"

.IX Header "BACKWARD COMPATIBILITY"

.IX Header "SEE ALSO"

.IX Header "CONTACT"