Describe how 32-bit and 64-bit versions of Emacs can be compiled on Solaris

systems.

etc/MACHINES

@@ -1021,11 +1021,25 @@ Sun 3, Sun 4 (sparc), Sun 386 (m68k-sun-sunos, sparc-sun-sunos, i386-sun-sunos,
 			       sparc-sun-sunos4.1.3noshr, sparc-sun-solaris2.*,
 			       i386-sun-solaris2.*, sparc*-*-linux-gnu)
 
+  To build a 32-bit Emacs (i.e. if you are having any sort of problem
+  bootstrapping a 64-bit version), you can use the Sun Studio compiler
+  and configure Emacs with:
+    env CC="cc -xarch=v7" CFLAGS='' ./configure    # on SPARC systems
+    env CC="cc -xarch=386" CFLAGS='' ./configure   # on x86 systems
+  On Solaris 2.10, it is also possible to use /usr/sfw/bin/gcc to build
+  a 32-bit version of Emacs.  Just make sure you point ./configure to
+  the right compiler:
+
+    env CC='/usr/sfw/bin/gcc -m32' ./configure
+
   To build a 64-bit Emacs (with larger maximum buffer size and
   including large file support) on a Solaris system which supports
   64-bit executables, use the Sun compiler, configuring something like
   this (see the cc documentation for information on 64-bit
-  compilation):  env CC="cc -xarch=v9" ./configure
+  compilation):
+
+    env CC="cc -xarch=v9" CFLAGS='' ./configure    # on SPARC systems
+    env CC="cc -xarch=amd64" CFLAGS='' ./configure # on x86 systems
 
   As of version 2.95, GCC doesn't support the 64-bit ABI properly, but
   later releases may.