+
+ <p>
+ The architecture we build on and build for is determined by make
+ variables via dpkg-architecture (see <ref id="dpkgarch">). You can
+ get the Debian architecture and the GNU style architecture
+ specification string for the build machine as well as the host
+ machine. Here is a list of supported make variables:
+ </p>
+
+ <list compact="compact">
+ <item>
+ <p><tt>DEB_*_ARCH</tt> (the Debian architecture)</p>
+ </item>
+ <item>
+ <p><tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
+ specification string)</p>
+ </item>
+ <item>
+ <p><tt>DEB_*_GNU_CPU</tt> (the CPU part of DEB_*_GNU_TYPE)</p>
+ </item>
+ <item>
+ <p><tt>DEB_*_GNU_SYSTEM</tt> (the System part of
+ DEB_*_GNU_TYPE)</p>
+ </list>
+
+ <p>
+ where <tt>*</tt> is either <tt>BUILD</tt> for specification of
+ the build machine or <tt>HOST</tt> for specification of the machine
+ we build for.
+ </p>
+
+ <p>
+ Backward compatibility can be provided in the rules file
+ by setting the needed variables to suitable default
+ values, please refer to the documentation of
+ dpkg-architecture for details.
+ </p>
+
+ <p>
+ It is important to understand that the <tt>DEB_*_ARCH</tt>
+ string does only determine which Debian architecture we
+ build on resp. for. It should not be used to get the CPU
+ or System information, the GNU style variables should be
+ used for that.
+ </p>