With this patch, dpkg understands the following syntax for debian/control
  (while maintaining full backwards compatibility).  Some examples:

    Build-Depends: bin86 [cpu: i386]

  ..where "bin86" is required only on _cpu_ i386 with any kernel (unlike [i386]
  which silently implies linux).

    Build-Depends: kernel-headers-2.4 [system: linux]

  ..where "kernel-headers-2.4" is required only on linux-gnu systems, on any
  cpu.

  Analogously, the "Architecture" field is split.  Some examples:

    Package: grub
    Cpu: i386
    System: any

    Package: modutils
    Cpu: any
    System: linux

diff -ur dpkg-1.10.26.old/scripts/controllib.pl dpkg-1.10.26/scripts/controllib.pl
--- dpkg-1.10.26.old/scripts/controllib.pl	2005-01-11 17:55:11.000000000 +0100
+++ dpkg-1.10.26/scripts/controllib.pl	2005-01-24 03:37:51.000000000 +0100
@@ -76,6 +76,15 @@
     $arch=`dpkg-architecture -qDEB_HOST_ARCH`;
     $? && &subprocerr("dpkg-architecture -qDEB_HOST_ARCH");
     chomp $arch;
+
+    $cpu=`dpkg-architecture -qDEB_HOST_GNU_CPU`;
+    $? && &subprocerr("dpkg-architecture -qDEB_HOST_GNU_CPU");
+    chomp $cpu;
+
+    $system=`dpkg-architecture -qDEB_HOST_GNU_SYSTEM`;
+    $? && &subprocerr("dpkg-architecture -qDEB_HOST_GNU_SYSTEM");
+    chomp $system;
+
     $substvar{'Arch'}= $arch;
 }
 
@@ -170,9 +179,9 @@
 sub parsedep {
     my ($dep_line, $use_arch, $reduce_arch) = @_;
     my @dep_list;
+    findarch;
     if (!$host_arch) {
-        $host_arch = `dpkg-architecture -qDEB_HOST_ARCH`;
-        chomp $host_arch;
+        $host_arch = $arch;
     }
     foreach my $dep_and (split(/,\s*/m, $dep_line)) {
         my @or_list = ();
@@ -182,6 +191,17 @@
             $package = $1 if ($dep_or =~ s/^([a-zA-Z0-9][a-zA-Z0-9+._-]*)\s*//m);
             ($relation, $version) = ($1, $2) if ($dep_or =~ s/^\((=|<=|>=|<<?|>>?)\s*([^)]+).*\)\s*//m);
             my @arches = split(/\s+/m, $1) if ($use_arch && $dep_or =~ s/^\[([^]]+)\]\s*//m);
+
+            if ($arches[0] eq 'cpu:') {
+              $host_arch = $cpu;
+            }
+            if ($arches[0] eq 'system:') {
+              $host_arch = $system;
+            }
+            if (($host_arch eq $cpu) || ($host_arch eq $system)) {
+              $arches = shift @arches;
+            }
+	    
             if ($reduce_arch && @arches) {
 
                 my $seen_arch='';
diff -ur dpkg-1.10.26.old/scripts/dpkg-gencontrol.pl dpkg-1.10.26/scripts/dpkg-gencontrol.pl
--- dpkg-1.10.26.old/scripts/dpkg-gencontrol.pl	2005-01-11 17:55:11.000000000 +0100
+++ dpkg-1.10.26/scripts/dpkg-gencontrol.pl	2005-01-24 02:01:25.000000000 +0100
@@ -46,7 +46,7 @@
 }
 
 $i=100;grep($fieldimps{$_}=$i--,
-          qw(Package Version Section Priority Architecture Essential
+          qw(Package Version Section Priority Architecture System Cpu Essential
              Pre-Depends Depends Recommends Suggests Enhances Optional 
 	     Conflicts Replaces Provides Installed-Size Origin Maintainer
 	     Bugs Source Description Build-Depends Build-Depends-Indep
@@ -144,6 +144,39 @@
                            " appear in package's list (@archlist)");
                 $f{$_}= $arch;
             }
+        } elsif (m/^Cpu$|^System$/) {
+            if (($_ eq 'System') && ($ccpu eq '')) {
+                $csystem= $v;
+            } elsif (($_ eq 'Cpu') && ($csystem eq '')) {
+                $ccpu= $v;
+            } else {
+                if ($ccpu eq '') { $ccpu= $v; } else { $csystem= $v; }
+                if ($ccpu eq 'all') {
+                    $f{Architecture}= 'all';
+                } elsif ($ccpu eq 'any') {
+		    if (($csystem eq 'all') || ($csystem eq 'any')) {
+		        $f{Architecture}= $arch;
+		    } else {
+		        @syslist= split(/\s+/,$csystem);
+                        grep($system eq $_, @syslist) ||
+			   &error("current build system $system does not".
+                           " appear in package's list (@syslist)");
+                        $f{Architecture}= $arch;
+		    }
+		} else {
+		    @cpulist= split(/\s+/,$ccpu);
+                    grep($cpu eq $_, @cpulist) ||
+		        &error("current build cpu $cpu does not".
+                        " appear in package's list (@cpulist)");
+		    if (!($csystem eq 'all') && !($csystem eq 'any')) {
+		        @syslist= split(/\s+/,$csystem);
+                        grep($system eq $_, @syslist) ||
+		            &error("current build system $system does not".
+                            " appear in package's list (@syslist)");
+		    }
+                    $f{Architecture}= $arch;
+		}
+            }
         } elsif (s/^X[CS]*B[CS]*-//i) {
             $f{$_}= $v;
         } elsif (!m/^X[CS]+-/i) {