Add libsdl2-dev dependency, spotted by @alokprasad at #5

README.md

@@ -46,6 +46,7 @@ The only advantage of using your host machine, is that you don't have to wait 2
 
 ## Do the right thing and use a virtual machine
 
+    sudo apt-get install libsdl2-dev
     sudo apt-get build-dep qemu
     ./run
 

run

@@ -43,8 +43,14 @@ cat ../buildroot_config_fragment >> "${outdir}/.config"
 make O="$outdir" olddefconfig
 # HOST_QEMU_OPTS is a hack that happens to work because the QEMU package luckly uses += at all times.
 # It shouldn't be necessary in the first place: https://bugs.busybox.net/show_bug.cgi?id=9936
+#
 # Even if were an autotools package, there is no general way currently to pass extra configs to it:
 # https://stackoverflow.com/questions/44341188/how-to-pass-extra-custom-configure-autotools-options-to-a-buildroot-package/44341225#44341225
+#
+# SDL support was rejected upstream because it adds many dependencies: https://patchwork.ozlabs.org/patch/770684/
+# We are just using the host SDL for now, if it causes too much problems we might remove it.
+# libsdl2-dev needs to be installed separatedly from sudo apt-get build-dep qemu
+# because Ubuntu 16.04's QEMU uses SDL 1.
 time \
   env \
   -u LD_LIBRARY_PATH \