told GCC what processor we're actually going to use
diff --git a/aos/build/aos.gypi b/aos/build/aos.gypi
index ca8d323..13a45b4 100644
--- a/aos/build/aos.gypi
+++ b/aos/build/aos.gypi
@@ -94,8 +94,7 @@
               ],
             }, {
               'cflags': [
-                #'-march=atom',
-                #'-mfpmath=sse',
+                '-mcpu=cortex-a8',
 
                 '-fstack-protector-all',
               ],
@@ -173,11 +172,9 @@
           ],
           'ldflags': [
             '-pthread',
-            #'-m32',
           ],
           'cflags': [
             '-pthread',
-            #'-m32',
 
             '-Wunused-local-typedefs',
 
diff --git a/aos/build/download_externals.sh b/aos/build/download_externals.sh
index 59005b5..4d712ff 100755
--- a/aos/build/download_externals.sh
+++ b/aos/build/download_externals.sh
@@ -8,10 +8,10 @@
 
 export CC=arm-linux-gnueabihf-gcc-4.7
 export CXX=arm-linux-gnueabihf-g++-4.7
+export CFLAGS=-mcpu=cortex-a8
+export CXXFLAGS=-mcpu=cortex-a8
 # Flags that should get passed to all configure scripts.
-# TODO(brians): If we're going to build everything ourselves, we should probably
-# optimize it for our target.
-CONFIGURE_FLAGS="--host=arm-linux-gnueabihf CC=${CC} CXX=${CXX}"
+CONFIGURE_FLAGS="--host=arm-linux-gnueabihf CC=${CC} CXX=${CXX} CFLAGS=${CFLAGS} CXXFLAGS=${CXXFLAGS}"
 
 TMPDIR=/tmp/$$-aos-tmpdir
 mkdir -p ${EXTERNALS}