recent versions of xulrunner have added the ability to explicitly specify various ARM build options such as hard or soft floating point as well as they type of VFP. We now specify those for ARM builds.

But not all the code uses these options but rather runs some tests to see if the processor supports NEON SIMD instructions. The problem with this is not ARM processors contain NEON capabilities and we need to be able to specify what options we want so we can run on as many platforms as possible.

xulrunner should only try to detect these sort of things if they aren't explicitly specified. 

in configure.in there's this section which detects the NEON and attempts to use it.

if test "$CPU_ARCH" = "arm"; then
  AC_MSG_CHECKING(for ARM SIMD support in compiler)
  # We try to link so that this also fails when
  # building with LTO.
  AC_TRY_LINK([],
                 [asm("uqadd8 r1, r1, r2");],
                 result="yes", result="no")
  AC_MSG_RESULT("$result")
  if test "$result" = "yes"; then
      AC_DEFINE(HAVE_ARM_SIMD)
      HAVE_ARM_SIMD=1
  fi

  AC_MSG_CHECKING(for ARM NEON support in compiler)
  # We try to link so that this also fails when
  # building with LTO.
  AC_TRY_LINK([],
                 [asm(".fpu neon\n vadd.i8 d0, d0, d0");],
                 result="yes", result="no")
  AC_MSG_RESULT("$result")
  if test "$result" = "yes"; then
      AC_DEFINE(HAVE_ARM_NEON)
      HAVE_ARM_NEON=1
  fi
fi # CPU_ARCH = arm

AC_SUBST(HAVE_ARM_SIMD)
AC_SUBST(HAVE_ARM_NEON)


The build errors we get are:

/usr/bin/python2.7 ../../config/pythonpath.py -I../../config ../../config/expandlibs_exec.py --uselist --  c++  -fno-rtti -Wall -Wpointer-arith -Woverloaded-virtual -Wsynth -Wno-ctor-dtor-privacy -Wno-non-virtual-dtor -Wno-invalid-offsetof -Wno-variadic-macros -Werror=return-type -pedantic -Wno-long-long -O2 -g -pipe -Wp,-D_FORTIFY_SOURCE=2 -fno-exceptions -fstack-protector --param=ssp-buffer-size=4 -march=armv7-a -mfpu=vfpv3-d16 -mfloat-abi=hard -fpermissive -march=armv7-a -mfpu=vfpv3-d16 -mfloat-abi=hard -fno-exceptions -fno-strict-aliasing -std=gnu++0x -pthread -ffunction-sections -fdata-sections -pipe  -DNDEBUG -DTRIMMED -g -Os -freorder-blocks  -fomit-frame-pointer -fPIC -shared -Wl,-z,defs -Wl,--gc-sections -Wl,-h,libxul.so -o libxul.so  nsStaticXULComponents.o nsUnicharUtils.o nsBidiUtils.o nsRDFResource.o    -lpthread    -Wl,-rpath-link,/builddir/build/BUILD/xulrunner-10.0.1/mozilla-release/dist/bin -Wl,-rpath-link,/usr/lib    ../../embedding/browser/gtk/src/libgtkembedmoz.a ../../toolkit/xre/libxulapp_s.a  ../../staticlib/components/libnecko.a ../../staticlib/components/libuconv.a ../../staticlib/components/libi18n.a ../../staticlib/components/libchardet.a ../../staticlib/components/libjar50.a ../../staticlib/components/libstartupcache.a ../../staticlib/components/libpref.a ../../staticlib/components/libhtmlpars.a ../../staticlib/components/libimglib2.a ../../staticlib/components/libgkgfx.a ../../staticlib/components/libgklayout.a ../../staticlib/components/libdocshell.a ../../staticlib/components/libembedcomponents.a ../../staticlib/components/libwebbrwsr.a ../../staticlib/components/libnsappshell.a ../../staticlib/components/libtxmgr.a ../../staticlib/components/libcommandlines.a ../../staticlib/components/libtoolkitcomps.a ../../staticlib/components/libpipboot.a ../../staticlib/components/libpipnss.a ../../staticlib/components/libappcomps.a ../../staticlib/components/libjsreflect.a ../../staticlib/components/libcomposer.a ../../staticlib/components/libjetpack_s.a ../../staticlib/components/libtelemetry.a ../../staticlib/components/libjsdebugger.a ../../staticlib/components/libstoragecomps.a ../../staticlib/components/librdf.a ../../staticlib/components/libwindowds.a ../../staticlib/components/libjsctypes.a ../../staticlib/components/libjsperf.a ../../staticlib/components/libgkplugin.a ../../staticlib/components/libunixproxy.a ../../staticlib/components/libjsd.a ../../staticlib/components/libautoconfig.a ../../staticlib/components/libauth.a ../../staticlib/components/libcookie.a ../../staticlib/components/libpermissions.a ../../staticlib/components/libuniversalchardet.a ../../staticlib/components/libfileview.a ../../staticlib/components/libplaces.a ../../staticlib/components/libtkautocomplete.a ../../staticlib/components/libsatchel.a ../../staticlib/components/libpippki.a ../../staticlib/components/libwidget_gtk2.a ../../staticlib/components/libsystem-pref.a ../../staticlib/components/libimgicon.a ../../staticlib/components/libaccessibility.a ../../staticlib/components/libremoteservice.a ../../staticlib/components/libspellchecker.a ../../staticlib/components/libzipwriter.a ../../staticlib/components/libservices-crypto.a ../../staticlib/libjsipc_s.a ../../staticlib/libdomipc_s.a ../../staticlib/libdomplugins_s.a ../../staticlib/libmozipc_s.a ../../staticlib/libmozipdlgen_s.a ../../staticlib/libipcshell_s.a ../../staticlib/libgfx2d.a ../../staticlib/libgfxipc_s.a ../../staticlib/libhal_s.a ../../staticlib/libxpcom_core.a ../../staticlib/libucvutil_s.a ../../staticlib/libchromium_s.a ../../staticlib/libmozreg_s.a ../../staticlib/libgtkxtbin.a ../../staticlib/libthebes.a ../../staticlib/libycbcr.a ../../staticlib/libangle.a  -L../../dist/bin -L../../dist/lib -ljpeg  ../../media/libpng/libmozpng.a ../../gfx/qcms/libmozqcms.a /builddir/build/BUILD/xulrunner-10.0.1/mozilla-release/dist/lib/libmozjs.a -Wl,-rpath-link,/usr/lib -L/usr/lib -lssl3 -lsmime3 -lnss3 -lnssutil3 -lcrmf -lcairo -lpixman-1 -lfreetype -lfontconfig    -lXrender -lcairo -lX11   ../../gfx/harfbuzz/src/libmozharfbuzz.a ../../gfx/ots/src/libmozots.a  ../../dist/lib/libmozsqlite3.a  -lz  -lhunspell-1.2   -L/usr/lib -lvpx -lasound   -lrt -L../../dist/bin -L../../dist/lib  -L/usr/lib -lplds4 -lplc4 -lnspr4 -lpthread -ldl ../../dist/lib/libmozalloc.a -pthread -L/lib -ldbus-glib-1 -ldbus-1 -lpthread -lgobject-2.0 -lgthread-2.0 -lrt -lglib-2.0    -lX11  -lXext  -pthread -lpangoft2-1.0 -lfreetype -lfontconfig -lpangocairo-1.0 -lpango-1.0 -lcairo -lgobject-2.0 -lgmodule-2.0 -lgthread-2.0 -lrt -lglib-2.0   -pthread -lgtk-x11-2.0 -latk-1.0 -lgio-2.0 -lpangoft2-1.0 -lfreetype -lfontconfig -lgdk-x11-2.0 -lpangocairo-1.0 -lgdk_pixbuf-2.0 -lpng12 -lm -lpango-1.0 -lcairo -lgmodule-2.0 -lgobject-2.0 -lgthread-2.0 -lrt -lglib-2.0   -lXt -lgthread-2.0 -lfreetype -lstartup-notification-1   -ldl  -lrt    
../../xpcom/base/nsSystemInfo.o: In function `mozilla::supports_edsp()':
/builddir/build/BUILD/xulrunner-10.0.1/mozilla-release/xpcom/base/../../dist/include/mozilla/arm.h:153: undefined reference to `mozilla::arm_private::edsp_enabled'
../../xpcom/base/nsSystemInfo.o: In function `mozilla::supports_armv6()':
/builddir/build/BUILD/xulrunner-10.0.1/mozilla-release/xpcom/base/../../dist/include/mozilla/arm.h:163: undefined reference to `mozilla::arm_private::armv6_enabled'
../../xpcom/base/nsSystemInfo.o: In function `mozilla::supports_neon()':
/builddir/build/BUILD/xulrunner-10.0.1/mozilla-release/xpcom/base/../../dist/include/mozilla/arm.h:173: undefined reference to `mozilla::arm_private::neon_enabled'
../../gfx/ycbcr/ycbcr_to_rgb565.o: In function `mozilla::gfx::ScaleYCbCrToRGB565(unsigned char const*, unsigned char const*, unsigned char const*, unsigned char*, int, int, int, int, int, int, int, int, int, mozilla::gfx::YUVType, mozilla::gfx::ScaleFilter)':
/builddir/build/BUILD/xulrunner-10.0.1/mozilla-release/gfx/ycbcr/ycbcr_to_rgb565.cpp:570: undefined reference to `mozilla::arm_private::neon_enabled'
../../gfx/ycbcr/ycbcr_to_rgb565.o: In function `mozilla::gfx::IsScaleYCbCrToRGB565Fast(int, int, int, int, int, int, mozilla::gfx::YUVType, mozilla::gfx::ScaleFilter)':
/builddir/build/BUILD/xulrunner-10.0.1/mozilla-release/gfx/ycbcr/ycbcr_to_rgb565.cpp:601: undefined reference to `mozilla::arm_private::neon_enabled'
../../gfx/ycbcr/ycbcr_to_rgb565.o: In function `mozilla::gfx::ConvertYCbCrToRGB565(unsigned char const*, unsigned char const*, unsigned char const*, unsigned char*, int, int, int, int, int, int, int, mozilla::gfx::YUVType)':
/builddir/build/BUILD/xulrunner-10.0.1/mozilla-release/gfx/ycbcr/ycbcr_to_rgb565.cpp:684: undefined reference to `mozilla::arm_private::neon_enabled'
../../gfx/ycbcr/ycbcr_to_rgb565.o: In function `mozilla::gfx::IsConvertYCbCrToRGB565Fast(int, int, int, int, mozilla::gfx::YUVType)':
/builddir/build/BUILD/xulrunner-10.0.1/mozilla-release/gfx/ycbcr/ycbcr_to_rgb565.cpp:697: undefined reference to `mozilla::arm_private::neon_enabled'
collect2: ld returned 1 exit status
make[5]: *** [libxul.so] Error 1

It appears with the addition of the ability to specify the ARM options some bits were missed. It would be awesome if we could have a patch to allow us to build xulrunner on ARM and move forward on F-17 building.