Index: doc/install.texi
===================================================================
--- doc/install.texi	(revision 194964)
+++ doc/install.texi	(working copy)
@@ -1813,6 +1813,16 @@ being used as the target C library.  Thi
 omitted from @file{libgcc.a} on the assumption that it will be provided by
 @samp{newlib}.
 
+@item --with-avrlibc
+Specifies that @samp{AVR-Libc} is
+being used as the target C library.  This causes float support
+functions like @code{__addsf3} to be omitted from @file{libgcc.a} on
+the assumption that it will be provided by @file{libm.a}.  For more
+technical details, cf. @uref{http://gcc.gnu.org/PR54461,,PR54461}.
+This option is only supported for the AVR target and only for
+non-RTEMS configurations.  The options is supported since version
+4.7.2 and is the default in 4.8.0 and newer.
+
 @item --with-build-time-tools=@var{dir}
 Specifies where to find the set of target tools (assembler, linker, etc.)
 that will be used while building GCC itself.  This option can be useful