Add a sect2 for "General Notes on Architectures".

I had assumed that everyone was aware of these considerations, but,
based on a conversation on ports-svn-commits, this is not the case.

This text does not change policy; it merely documents existing
technology.

1 files changed, 20 insertions, 0 deletions

diff --git a/en_US.ISO8859-1/books/porters-handbook/porting-dads/chapter.xml b/en_US.ISO8859-1/books/porters-handbook/porting-dads/chapter.xml
index 5c3fa42950..2719f12388 100644
--- a/en_US.ISO8859-1/books/porters-handbook/porting-dads/chapter.xml
+++ b/en_US.ISO8859-1/books/porters-handbook/porting-dads/chapter.xml
@@ -520,6 +520,26 @@ cc -o someprogram source1.o source2.o -L/usr/local/lib -lsomelib</programlisting
   <sect1 xml:id="dads-arch">
     <title>Architectural Considerations</title>
 
+    <sect2 xml:id="dads-arch-general">
+      <title>General Notes on Architectures</title>
+
+      <para>&os; runs on many more processor architectures than
+	just the well-known x86-based ones.  Some ports have
+	constraints which are particular to one or more of these
+	architectures.</para>
+
+      <para>For the list of supported architectures, run:</para>
+
+      <programlisting>cd ${SRCDIR}; make targets</programlisting>
+
+      <para>The values are shown in the form
+	<literal>TARGET</literal>/<literal>TARGET_ARCH</literal>.
+	The ports read-only makevar <literal>ARCH</literal> is set
+	based on the value of <literal>TARGET_ARCH</literal>.
+	Port <filename>Makefile</filename>s should test the value
+	of this Makevar.</para>
+    </sect2>
+
     <sect2 xml:id="dads-arch-neutral">
       <title>Marking a Port as Architecture Neutral</title>