diff --git a/Config.mk b/Config.mk
index 6e4eb2f..43b70f7 100644
--- a/Config.mk
+++ b/Config.mk
@@ -2,10 +2,6 @@
 # Build configuration
 #
 
-# Paths to ARM toolchains
-ARM_HOME?=$(HOME)/arm-gnu-toolchain-11.3.rel1-x86_64-arm-none-eabi
-AARCH64_HOME?=$(HOME)/arm-gnu-toolchain-11.3.rel1-x86_64-aarch64-none-elf
-
 # Valid options: pi3, pi3-64, pi4, pi4-64
 BOARD?=pi3-64
 HDMI_CONSOLE?=0
@@ -22,36 +18,47 @@ GC_SECTIONS?=1
 ifeq ($(BOARD), pi2)
 RASPBERRYPI=2
 BITS=32
+CPU_FLAGS=-mcpu=cortex-a7 -marm -mfpu=neon-vfpv4 -mfloat-abi=hard
 PREFIX=arm-none-eabi-
 KERNEL=kernel7
 else ifeq ($(BOARD), pi3)
 RASPBERRYPI=3
 BITS=32
+CPU_FLAGS=-mcpu=cortex-a53 -marm -mfpu=neon-fp-armv8 -mfloat-abi=hard
 PREFIX=arm-none-eabi-
 KERNEL=kernel8-32
 else ifeq ($(BOARD), pi3-64)
 RASPBERRYPI=3
 BITS=64
+CPU_FLAGS=-mcpu=cortex-a53 -mlittle-endian
 PREFIX=aarch64-none-elf-
 KERNEL=kernel8
 else ifeq ($(BOARD), pi4)
 RASPBERRYPI=4
 BITS=32
+CPU_FLAGS=-mcpu=cortex-a72 -marm -mfpu=neon-fp-armv8 -mfloat-abi=hard
 PREFIX=arm-none-eabi-
 KERNEL=kernel7l
 else ifeq ($(BOARD), pi4-64)
 RASPBERRYPI=4
 BITS=64
+CPU_FLAGS=-mcpu=cortex-a72 -mlittle-endian
 PREFIX=aarch64-none-elf-
 KERNEL=kernel8-rpi4
 else
 $(error Invalid board type "$(BOARD)"; please specify one of [ pi2 | pi3 | pi3-64 | pi4 | pi4-64 ])
 endif
 
+# Compiler flags for external dependencies
+CFLAGS_EXTERNAL = $(CPU_FLAGS)
+ifeq ($(strip $(GC_SECTIONS)),1)
+CFLAGS_EXTERNAL += -ffunction-sections -fdata-sections
+endif
+
 ifeq ($(PREFIX), arm-none-eabi-)
-CMAKE_TOOLCHAIN_FLAGS=-DARM_HOME=$(ARM_HOME) -DCMAKE_TOOLCHAIN_FILE=../cmake/arm-none-eabi.cmake
+CMAKE_TOOLCHAIN_FLAGS=-DCMAKE_TOOLCHAIN_FILE=../cmake/arm-none-eabi.cmake
 else
-CMAKE_TOOLCHAIN_FLAGS=-DAARCH64_HOME=$(AARCH64_HOME) -DCMAKE_TOOLCHAIN_FILE=../cmake/aarch64-none-elf.cmake
+CMAKE_TOOLCHAIN_FLAGS=-DCMAKE_TOOLCHAIN_FILE=../cmake/aarch64-none-elf.cmake
 endif
 
 # Paths
@@ -61,6 +68,7 @@ CIRCLE_STDLIB_CONFIG=$(CIRCLESTDLIBHOME)/Config.mk
 CIRCLEHOME=$(CIRCLESTDLIBHOME)/libs/circle
 CIRCLE_CONFIG=$(CIRCLEHOME)/Config.mk
 
+NEWLIB_ARCH=$(firstword $(subst -, ,$(PREFIX)))-none-circle
 NEWLIBDIR=$(CIRCLESTDLIBHOME)/install/$(NEWLIB_ARCH)
 CIRCLE_STDLIB_LIBS=$(NEWLIBDIR)/lib/libm.a \
 				   $(NEWLIBDIR)/lib/libc.a \
@@ -85,5 +93,3 @@ FLUIDSYNTHBUILDDIR=build-fluidsynth
 FLUIDSYNTHLIB=$(FLUIDSYNTHBUILDDIR)/src/libfluidsynth.a
 
 INIHHOME=$(realpath external/inih)
-
--include $(CIRCLE_STDLIB_CONFIG)
diff --git a/Makefile b/Makefile
index 3b17f5b..05de6e7 100644
--- a/Makefile
+++ b/Makefile
@@ -5,7 +5,7 @@
 include Config.mk
 
 .DEFAULT_GOAL=all
-.PHONY: circle-stdlib mt32emu fluidsynth all clean veryclean
+.PHONY: submodules circle-stdlib mt32emu fluidsynth all clean veryclean
 
 #
 # Functions to apply/reverse patches only if not completely applied/reversed already
@@ -26,6 +26,14 @@ REVERSE_PATCH=sh -c '																\
 		patch --reverse --strip 1 --no-backup-if-mismatch -r - --directory $$1 < $$2 || (echo "Patch $$2 failed" >&2 && exit 1);	\
 	fi' REVERSE_PATCH
 
+#
+# Get submodules
+#
+submodules:
+	@git submodule update --init --depth 1
+	@git -C external/circle-stdlib submodule update --init --depth 1 libs/circle libs/circle-newlib
+	@git -C external/circle-stdlib/libs/circle submodule update --init --depth 1 addon/wlan/hostap
+
 #
 # Configure circle-stdlib
 #
@@ -69,8 +77,8 @@ $(CIRCLESTDLIBHOME)/.done: $(CIRCLE_STDLIB_CONFIG)
 mt32emu: $(MT32EMUBUILDDIR)/.done
 
 $(MT32EMUBUILDDIR)/.done: $(CIRCLESTDLIBHOME)/.done
-	@CFLAGS="$(CFLAGS_FOR_TARGET)" \
-	CXXFLAGS="$(CFLAGS_FOR_TARGET)" \
+	@CFLAGS="$(CFLAGS_EXTERNAL)" \
+	CXXFLAGS="$(CFLAGS_EXTERNAL)" \
 	cmake  -B $(MT32EMUBUILDDIR) \
 			$(CMAKE_TOOLCHAIN_FLAGS) \
 			-DCMAKE_CXX_FLAGS_RELEASE="-Ofast" \
@@ -90,7 +98,7 @@ fluidsynth: $(FLUIDSYNTHBUILDDIR)/.done
 $(FLUIDSYNTHBUILDDIR)/.done: $(CIRCLESTDLIBHOME)/.done
 	@${APPLY_PATCH} $(FLUIDSYNTHHOME) patches/fluidsynth-2.3.1-circle.patch
 
-	@CFLAGS="$(CFLAGS_FOR_TARGET)" \
+	@CFLAGS="$(CFLAGS_EXTERNAL)" \
 	cmake  -B $(FLUIDSYNTHBUILDDIR) \
 			$(CMAKE_TOOLCHAIN_FLAGS) \
 			-DCMAKE_C_FLAGS_RELEASE="-Ofast -fopenmp-simd" \
@@ -138,14 +146,14 @@ clean:
 #
 # Clean kernel and all dependencies
 #
-veryclean: clean
+mrproper: clean
 # Reverse patches
 	@${REVERSE_PATCH} $(CIRCLEHOME) patches/circle-45-cp210x-remove-partnum-check.patch
 	@${REVERSE_PATCH} $(CIRCLEHOME) patches/circle-45-minimal-usb-drivers.patch
 	@${REVERSE_PATCH} $(FLUIDSYNTHHOME) patches/fluidsynth-2.3.1-circle.patch
 
 # Clean circle-stdlib
-	@$(MAKE) -C $(CIRCLESTDLIBHOME) mrproper
+	@if [ -f $(CIRCLE_STDLIB_CONFIG) ]; then $(MAKE) -C $(CIRCLESTDLIBHOME) mrproper; fi
 	@$(RM) $(CIRCLESTDLIBHOME)/.done
 
 # Clean mt32emu
diff --git a/cmake/aarch64-none-elf.cmake b/cmake/aarch64-none-elf.cmake
index 4edebac..2780a90 100644
--- a/cmake/aarch64-none-elf.cmake
+++ b/cmake/aarch64-none-elf.cmake
@@ -3,5 +3,5 @@ set(CMAKE_SYSTEM_PROCESSOR aarch64)
 
 set(CMAKE_TRY_COMPILE_TARGET_TYPE STATIC_LIBRARY)
 
-set(CMAKE_C_COMPILER ${AARCH64_HOME}/bin/aarch64-none-elf-gcc)
-set(CMAKE_CXX_COMPILER ${AARCH64_HOME}/bin/aarch64-none-elf-g++)
+set(CMAKE_C_COMPILER aarch64-none-elf-gcc)
+set(CMAKE_CXX_COMPILER aarch64-none-elf-g++)
diff --git a/cmake/arm-none-eabi.cmake b/cmake/arm-none-eabi.cmake
index 7c717dc..1cc765b 100644
--- a/cmake/arm-none-eabi.cmake
+++ b/cmake/arm-none-eabi.cmake
@@ -3,5 +3,5 @@ set(CMAKE_SYSTEM_PROCESSOR arm)
 
 set(CMAKE_TRY_COMPILE_TARGET_TYPE STATIC_LIBRARY)
 
-set(CMAKE_C_COMPILER ${ARM_HOME}/bin/arm-none-eabi-gcc)
-set(CMAKE_CXX_COMPILER ${ARM_HOME}/bin/arm-none-eabi-g++)
+set(CMAKE_C_COMPILER arm-none-eabi-gcc)
+set(CMAKE_CXX_COMPILER arm-none-eabi-g++)