notes about which versions of GHC can be used to bootstrap

diff --git a/docs/building/building.xml b/docs/building/building.xml
index 04cf05e..054b9e8 100644 (file)
--- a/docs/building/building.xml
+++ b/docs/building/building.xml
@@ -165,10 +165,15 @@
          supported method, and you may encounter difficulties.  Full
          instructions are in <xref linkend="sec-porting-ghc"/>.</para>
 
-         <para>Which version of GHC you need will depend on the
-         packages you intend to build.  GHC itself will normally
-         build using one of several older versions of itself - check
-         the announcement or release notes for details.</para>
+         <para>GHC can be built using either an earlier released
+         version of GHC (currently 5.04 and later are supported), or
+         bootstrapped using a GHC built from exactly the same
+         sources.  Note that this means you cannot in general build
+         GHC using an arbitrary development snapshot, or a build from
+         say last week.  It might work, it might not - we don't
+         guarantee anything.  To be on the safe side, start your
+         build using the most recently released stable version of
+         GHC.</para>
        </listitem>
       </varlistentry>