-(@file{xm.h} is a link to this file, created by @code{configure}). Contains C
-macro definitions describing the host system environment, such as byte
-order, host C compiler and library.
+This file once contained definitions and includes required when hosting
+gdb on machine @var{xyz}. Those definitions and includes are now
+handled by Autoconf.
+
+New host and native configurations do not need this file.
+
+@emph{Maintainer's note: Some hosts continue to use the @file{xm-xyz.h}
+file to define the macros @var{HOST_FLOAT_FORMAT},
+@var{HOST_DOUBLE_FORMAT} and @var{HOST_LONG_DOUBLE_FORMAT}. That code
+also needs to be replaced with either an Autoconf or run-time test.}