tools/firmware: Build firmware as -ffreestanding

firmware should always have been -ffreestanding, as it doesn't execute in the
host environment.  -ffreestanding implies -fno-builtin, so replace the option.

inttypes.h isn't a freestanding header, but the 32bitbios_support.c only wants
the stdint.h types so switch to the more appropriate include.

This removes the build time dependency on a 32bit libc just to compile the
hvmloader and friends.

Update README and the TravisCI configuration.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Ian Jackson <iwj@xenproject.org>
Release-Acked-by: Ian Jackson <iwj@xenproject.org>

.travis.yml

@@ -58,7 +58,6 @@ addons:
             - acpica-tools
             - bin86
             - bcc
-            - libc6-dev-i386
             - libnl-3-dev
             - ocaml-nox
             - libfindlib-ocaml-dev

README

@@ -62,9 +62,6 @@ provided by your OS distributor:
     * GNU bison and GNU flex
     * GNU gettext
     * ACPI ASL compiler (iasl)
-    * Libc multiarch package (e.g. libc6-dev-i386 / glibc-devel.i686).
-      Required when building on a 64-bit platform to build
-      32-bit components which are enabled on a default build.
 
 In addition to the above there are a number of optional build
 prerequisites. Omitting these will cause the related features to be

tools/firmware/Rules.mk

@@ -16,4 +16,4 @@ CFLAGS += -Werror
 $(call cc-options-add,CFLAGS,CC,$(EMBEDDED_EXTRA_CFLAGS))
 
 # Extra CFLAGS suitable for an embedded type of environment.
-CFLAGS += -fno-builtin -msoft-float
+CFLAGS += -ffreestanding -msoft-float

tools/firmware/hvmloader/32bitbios_support.c

@@ -20,7 +20,7 @@
  * this program; If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include <inttypes.h>
+#include <stdint.h>
 #include <xen/libelf/elfstructs.h>
 
 #include "util.h"