diff --git a/.gitignore b/.gitignore
index 59ad636..a9264d0 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,6 +1,7 @@
-/.sdk_patch_*
-/esp_iot_sdk_v*/
-/esp_iot_sdk_v*.zip
-/ESP8266_NONOS_SDK_V1.5.1_16_01_08.zip
-/sdk
-/xtensa-lx106-elf/
+.sdk_patch_*
+sdk
+xtensa-lx106-elf/
+.sdk_dir_*
+esp_nonos_sdk_*
+ESP8266_NONOS_SDK-*.zip
+*.o
diff --git a/Makefile b/Makefile
index 9ad6f95..b7f2802 100644
--- a/Makefile
+++ b/Makefile
@@ -4,17 +4,34 @@
 # which can be used with multiple SDK versions.
 STANDALONE = y
 
+GCC_VERSION = 7.3.0
+CT_GCC_VERSION = 7_3_0
+
 # Directory to install toolchain to, by default inside current dir.
 TOOLCHAIN = $(TOP)/xtensa-lx106-elf
 
+# NOTE: Leave this as-is and use full shas above to simplfiy things.
+# Instead of all the makefile hacks that break every time, just
+# always call it master, then d/l the SDK as a zip based on SHA.
+VENDOR_SDK = master
 
-# Vendor SDK version to install, see VENDOR_SDK_ZIP_* vars below
-# for supported versions.
-VENDOR_SDK = 2.1.0-18-g61248df
-
-.PHONY: crosstool-NG toolchain libhal libcirom sdk
+########################### SDK Commit List ############################
+## Pre-Krack      - 10aea1782b2cac518a1a30eb8b4e046ed76c8d7c           #
+## Krack patch    - 61248df5f6d45d130313b412f7492f581fd4cadf           #
+## master@10d7772 - 10d777260264f658965c5f323ae7f6741074d50e           #
+## master@4899e50 - 4671b17cc9fc6ed6787c2d310daf8accccf29c8d           #
+## master@4899e50 - 0e2308ff41578f6ad9a73f805ac4a441747d2a8e           #
+## master@cab958d - 779294b0a220a6bd72c73963d890c2f1d9116b5e           #
+## ------------------------- v2.2.0 release -------------------------- #
+## master@fcdedd6 - f2c63854331c8d46f7ffe944f6697ab204a54379 <-- curr. #
+########################################################################
 
+REPO_TAG          :=v2.2.1
+VENDOR_FULL_SHA   :=3ea90190d3092131505c97ac0ddb41d5e8bedefc
+VENDOR_GIT_ZIP    :="ESP8266_NONOS_SDK-$(VENDOR_FULL_SHA).zip"
+VENDOR_ZIP_DL_URI :="https://github.com/someburner/ESP8266_NONOS_SDK/releases/download/$(REPO_TAG)/$(VENDOR_GIT_ZIP)"
 
+.PHONY: crosstool-ng esptool toolchain _libhal libs sdk liblwip postbuild
 
 TOP = $(PWD)
 SHELL = /bin/bash
@@ -22,16 +39,23 @@ PATCH = patch -b -N
 UNZIP = unzip -q -o
 VENDOR_SDK_ZIP = $(VENDOR_SDK_ZIP_$(VENDOR_SDK))
 VENDOR_SDK_DIR = $(VENDOR_SDK_DIR_$(VENDOR_SDK))
+VENDOR_ZIP_DIR = $(VENDOR_ZIP_DIR_$(VENDOR_SDK))
 
-VENDOR_SDK_DIR_2.1.0-18-g61248df = ESP8266_NONOS_SDK-2.1.0-18-g61248df
+VENDOR_SDK_ZIP_master = ESP8266_NONOS_SDK-master.zip
+VENDOR_ZIP_DIR_master = ESP8266_NONOS_SDK-master
+VENDOR_SDK_DIR_master = esp_nonos_sdk_master
 VENDOR_SDK_ZIP_2.1.0 = ESP8266_NONOS_SDK-2.1.0.zip
-VENDOR_SDK_DIR_2.1.0 = ESP8266_NONOS_SDK-2.1.0
+VENDOR_ZIP_DIR_2.1.0 = ESP8266_NONOS_SDK-2.1.0
+VENDOR_SDK_DIR_2.1.0 = esp_nonos_sdk_v2.1.0
 VENDOR_SDK_ZIP_2.0.0 = ESP8266_NONOS_SDK_V2.0.0_16_08_10.zip
-VENDOR_SDK_DIR_2.0.0 = ESP8266_NONOS_SDK_V2.0.0_16_08_10
+VENDOR_ZIP_DIR_2.0.0 = ESP8266_NONOS_SDK_V2.0.0_16_08_10
+VENDOR_SDK_DIR_2.0.0 = esp_nonos_sdk_v2.0.0
 VENDOR_SDK_ZIP_1.5.4 = ESP8266_NONOS_SDK_V1.5.4_16_05_20.zip
-VENDOR_SDK_DIR_1.5.4 = ESP8266_NONOS_SDK_V1.5.4_16_05_20
+VENDOR_ZIP_DIR_1.5.4 = ESP8266_NONOS_SDK_V1.5.4_16_05_20
+VENDOR_SDK_DIR_1.5.4 = esp_nonos_sdk_v1.5.4
 VENDOR_SDK_ZIP_1.5.3 = ESP8266_NONOS_SDK_V1.5.3_16_04_18.zip
-VENDOR_SDK_DIR_1.5.3 = ESP8266_NONOS_SDK_V1.5.3_16_04_18/ESP8266_NONOS_SDK
+VENDOR_ZIP_DIR_1.5.3 = ESP8266_NONOS_SDK_V1.5.3_16_04_18/ESP8266_NONOS_SDK
+VENDOR_SDK_DIR_1.5.3 = esp_nonos_sdk_v1.5.3
 VENDOR_SDK_ZIP_1.5.2 = ESP8266_NONOS_SDK_V1.5.2_16_01_29.zip
 VENDOR_SDK_DIR_1.5.2 = esp_iot_sdk_v1.5.2
 VENDOR_SDK_ZIP_1.5.1 = ESP8266_NONOS_SDK_V1.5.1_16_01_08.zip
@@ -72,9 +96,7 @@ VENDOR_SDK_DIR_0.9.3 = esp_iot_sdk_v0.9.3
 VENDOR_SDK_ZIP_0.9.2 = esp_iot_sdk_v0.9.2_14_10_24.zip
 VENDOR_SDK_DIR_0.9.2 = esp_iot_sdk_v0.9.2
 
-
-
-all: esptool libcirom standalone sdk sdk_patch $(TOOLCHAIN)/xtensa-lx106-elf/sysroot/usr/lib/libhal.a $(TOOLCHAIN)/bin/xtensa-lx106-elf-gcc lwip
+all: toolchain esptool sdk libs liblwip postbuild
 	@echo
 	@echo "Xtensa toolchain is built, to use it:"
 	@echo
@@ -91,56 +113,42 @@ else
 	@echo
 endif
 
-standalone: sdk sdk_patch toolchain
-ifeq ($(STANDALONE),y)
-	@echo "Installing vendor SDK headers into toolchain sysroot"
-	@cp -Rf sdk/include/* $(TOOLCHAIN)/xtensa-lx106-elf/sysroot/usr/include/
-	@echo "Installing vendor SDK libs into toolchain sysroot"
-	@cp -Rf sdk/lib/* $(TOOLCHAIN)/xtensa-lx106-elf/sysroot/usr/lib/
-	@echo "Installing vendor SDK linker scripts into toolchain sysroot"
-	@sed -e 's/\r//' sdk/ld/eagle.app.v6.ld | sed -e s@../ld/@@ >$(TOOLCHAIN)/xtensa-lx106-elf/sysroot/usr/lib/eagle.app.v6.ld
-	@sed -e 's/\r//' sdk/ld/eagle.rom.addr.v6.ld >$(TOOLCHAIN)/xtensa-lx106-elf/sysroot/usr/lib/eagle.rom.addr.v6.ld
-endif
+esptool: $(TOOLCHAIN)/bin/esptool.py
 
-clean: clean-sdk
-	$(MAKE) -C crosstool-NG clean MAKELEVEL=0
-	-rm -rf crosstool-NG/.build/src
-	-rm -f crosstool-NG/local-patches/gcc/4.8.5/1000-*
-	-rm -rf $(TOOLCHAIN)
-
-clean-sdk:
-	rm -rf $(VENDOR_SDK_DIR)
-	rm -f sdk
-	rm -f .sdk_patch_$(VENDOR_SDK)
-	rm -f user_rf_cal_sector_set.o empty_user_rf_pre_init.o
-	$(MAKE) -C esp-open-lwip -f Makefile.open clean
-
-clean-sysroot:
-	rm -rf $(TOOLCHAIN)/xtensa-lx106-elf/sysroot/usr/lib/*
-	rm -rf $(TOOLCHAIN)/xtensa-lx106-elf/sysroot/usr/include/*
-
-
-esptool: toolchain
+$(TOOLCHAIN)/bin/esptool.py:
 	cp esptool/esptool.py $(TOOLCHAIN)/bin/
 
 toolchain: $(TOOLCHAIN)/bin/xtensa-lx106-elf-gcc
+#	cp strip_libgcc_funcs.txt $(TOOLCHAIN)/lib/gcc/xtensa-lx106-elf/$(GCC_VERSION)/
+#	cd $(TOOLCHAIN)/lib/gcc/xtensa-lx106-elf/$(GCC_VERSION)/; $(TOOLCHAIN)/bin/xtensa-lx106-elf-ar -M < strip_libgcc_funcs.txt; rm strip_libgcc_funcs.txt
+#	cp strip_libc_funcs.txt $(TOOLCHAIN)/xtensa-lx106-elf/lib
+#	cd $(TOOLCHAIN)/xtensa-lx106-elf/lib; $(TOOLCHAIN)/bin/xtensa-lx106-elf-ar -M < strip_libc_funcs.txt; rm strip_libc_funcs.txt
 
-$(TOOLCHAIN)/bin/xtensa-lx106-elf-gcc: crosstool-NG/ct-ng
-	cp -f 1000-mforce-l32.patch crosstool-NG/local-patches/gcc/4.8.5/
-	$(MAKE) -C crosstool-NG -f ../Makefile _toolchain
+$(TOOLCHAIN)/bin/xtensa-lx106-elf-gcc: crosstool-ng/ct-ng
+	$(MAKE) -C crosstool-ng -f ../Makefile _toolchain
 
 _toolchain:
 	./ct-ng xtensa-lx106-elf
 	sed -r -i.org s%CT_PREFIX_DIR=.*%CT_PREFIX_DIR="$(TOOLCHAIN)"% .config
-	sed -r -i s%CT_INSTALL_DIR_RO=y%"#"CT_INSTALL_DIR_RO=y% .config
+	sed -r -i s%CT_PREFIX_DIR_RO=y%"#"CT_PREFIX_DIR_RO=y% .config
+	@echo "Setting CT_GCC Version: $(GCC_VERSION)"
+	# Clear autogenerated GCC settings
+	sed -r -i s%CT_GCC_V_.*=y%% .config
+	sed -r -i s%CT_GCC_VERSION=.*%% .config
+	sed -r -i s%"# "CT_GCC_V_$(CT_GCC_VERSION)" is not set"%% .config
+	# Set GCC version
+	echo "CT_GCC_V_$(CT_GCC_VERSION)=y" >> .config
+	echo "CT_CC_GCC_V_$(CT_GCC_VERSION)=y" >> .config
+	echo "CT_GCC_VERSION=\"$(GCC_VERSION)\"" >> .config
+	# Append overrides
 	cat ../crosstool-config-overrides >> .config
+	# Build
 	./ct-ng build
 
+crosstool-ng: crosstool-ng/ct-ng
 
-crosstool-NG: crosstool-NG/ct-ng
-
-crosstool-NG/ct-ng: crosstool-NG/bootstrap
-	$(MAKE) -C crosstool-NG -f ../Makefile _ct-ng
+crosstool-ng/ct-ng: crosstool-ng/bootstrap
+	$(MAKE) -C crosstool-ng -f ../Makefile _ct-ng
 
 _ct-ng:
 	./bootstrap
@@ -148,63 +156,113 @@ _ct-ng:
 	$(MAKE) MAKELEVEL=0
 	$(MAKE) install MAKELEVEL=0
 
-crosstool-NG/bootstrap:
+crosstool-ng/bootstrap:
 	@echo "You cloned without --recursive, fetching submodules for you."
 	git submodule update --init --recursive
 
-libcirom: $(TOOLCHAIN)/xtensa-lx106-elf/sysroot/lib/libcirom.a
+$(TOOLCHAIN)/lib/gcc/xtensa-lx106-elf/$(GCC_VERSION)/libgcc.a.orig: $(TOOLCHAIN)/lib/gcc/xtensa-lx106-elf/$(GCC_VERSION)/libgcc.a
+	cp strip_libgcc_funcs.txt $(@D)
+	cd $(@D); cp -f libgcc.a libgcc.a.orig; $(TOOLCHAIN)/bin/xtensa-lx106-elf-ar -M < strip_libgcc_funcs.txt; rm strip_libgcc_funcs.txt
 
-$(TOOLCHAIN)/xtensa-lx106-elf/sysroot/lib/libcirom.a: $(TOOLCHAIN)/xtensa-lx106-elf/sysroot/lib/libc.a $(TOOLCHAIN)/bin/xtensa-lx106-elf-gcc
+$(TOOLCHAIN)/xtensa-lx106-elf/lib/libc.a.orig: $(TOOLCHAIN)/xtensa-lx106-elf/lib/libc.a
+	cp strip_libc_funcs.txt $(TOOLCHAIN)/xtensa-lx106-elf/lib
+	cd $(TOOLCHAIN)/xtensa-lx106-elf/lib; cp -f libc.a libc.a.orig; $(TOOLCHAIN)/bin/xtensa-lx106-elf-ar -M < strip_libc_funcs.txt; rm strip_libc_funcs.txt
+
+$(TOOLCHAIN)/xtensa-lx106-elf/usr/lib/libcirom.a: $(TOOLCHAIN)/xtensa-lx106-elf/lib/libc.a
 	@echo "Creating irom version of libc..."
-	$(TOOLCHAIN)/bin/xtensa-lx106-elf-objcopy --rename-section .text=.irom0.text \
-		--rename-section .literal=.irom0.literal $(<) $(@);
+	$(TOOLCHAIN)/bin/xtensa-lx106-elf-objcopy --rename-section .text=.irom0.text --rename-section .literal=.irom0.literal $(<) $(@);
 
-libhal: $(TOOLCHAIN)/xtensa-lx106-elf/sysroot/usr/lib/libhal.a
+$(TOOLCHAIN)/xtensa-lx106-elf/usr/lib/libmirom.a: $(TOOLCHAIN)/xtensa-lx106-elf/lib/libm.a
+	@echo "Creating irom version of libm..."
+	$(TOOLCHAIN)/bin/xtensa-lx106-elf-objcopy --rename-section .text=.irom0.text --rename-section .literal=.irom0.literal $(<) $(@);
 
-$(TOOLCHAIN)/xtensa-lx106-elf/sysroot/usr/lib/libhal.a: $(TOOLCHAIN)/bin/xtensa-lx106-elf-gcc
-	$(MAKE) -C lx106-hal -f ../Makefile _libhal
+$(TOOLCHAIN)/xtensa-lx106-elf/usr/lib/libhal.a: $(TOOLCHAIN)/bin/xtensa-lx106-elf-gcc
+	make -C lx106-hal -f ../Makefile _libhal
 
 _libhal:
 	autoreconf -i
-	PATH="$(TOOLCHAIN)/bin:$(PATH)" ./configure --host=xtensa-lx106-elf --prefix=$(TOOLCHAIN)/xtensa-lx106-elf/sysroot/usr
-	PATH="$(TOOLCHAIN)/bin:$(PATH)" $(MAKE)
-	PATH="$(TOOLCHAIN)/bin:$(PATH)" $(MAKE) install
+	PATH="$(TOOLCHAIN)/bin:$(PATH)" ./configure --host=xtensa-lx106-elf --prefix=$(TOOLCHAIN)/xtensa-lx106-elf/usr
+	PATH="$(TOOLCHAIN)/bin:$(PATH)" make
+	PATH="$(TOOLCHAIN)/bin:$(PATH)" make install
 
+liblwip: $(TOOLCHAIN)/xtensa-lx106-elf/usr/lib/liblwip_open.a
 
+$(TOOLCHAIN)/xtensa-lx106-elf/usr/lib/liblwip_open.a: $(TOOLCHAIN)/bin/xtensa-lx106-elf-gcc
+	make -C esp-open-lwip -f Makefile.open all \
+		CC=$(TOOLCHAIN)/bin/xtensa-lx106-elf-gcc \
+		AR=$(TOOLCHAIN)/bin/xtensa-lx106-elf-ar \
+		PREFIX=$(TOOLCHAIN) \
+		CFLAGS_EXTRA=-I$(TOP)/sdk/include
+	cp esp-open-lwip/liblwip_open.a $(TOOLCHAIN)/xtensa-lx106-elf/usr/lib
+	cp -a esp-open-lwip/include/arch esp-open-lwip/include/lwip esp-open-lwip/include/netif esp-open-lwip/include/lwipopts.h \
+		$(TOOLCHAIN)/xtensa-lx106-elf/usr/include/
+	cp -a esp-open-lwip/include/arch esp-open-lwip/include/lwip esp-open-lwip/include/netif esp-open-lwip/include/lwipopts.h \
+		$(TOOLCHAIN)/xtensa-lx106-elf/sys-include/
 
-sdk: $(VENDOR_SDK_DIR)/.dir
+libs: $(TOOLCHAIN)/xtensa-lx106-elf/usr/lib/libhal.a $(TOOLCHAIN)/xtensa-lx106-elf/lib/libc.a.orig $(TOOLCHAIN)/xtensa-lx106-elf/usr/lib/libcirom.a $(TOOLCHAIN)/xtensa-lx106-elf/usr/lib/libmirom.a $(TOOLCHAIN)/lib/gcc/xtensa-lx106-elf/$(GCC_VERSION)/libgcc.a.orig
+
+sdk: .sdk_dir_$(VENDOR_SDK) .sdk_patch_$(VENDOR_SDK)
 	ln -snf $(VENDOR_SDK_DIR) sdk
+ifeq ($(STANDALONE), y)
+	@echo "Installing vendor SDK headers into toolchain"
+	@mkdir -p $(TOOLCHAIN)/xtensa-lx106-elf/usr/include
+	@cp -Rf sdk/include/* $(TOOLCHAIN)/xtensa-lx106-elf/usr/include/
+	@echo "Installing vendor SDK libs into toolchain"
+	@cp -Rf $(VENDOR_SDK_DIR)/lib/* $(TOOLCHAIN)/xtensa-lx106-elf/usr/lib/
+	@rm -f $(TOOLCHAIN)/xtensa-lx106-elf/usr/lib/libgcc.a
+	@rm -f $(TOOLCHAIN)/xtensa-lx106-elf/usr/lib/libc.a
+	@echo "Installing vendor SDK linker scripts into toolchain"
+	@sed -e 's/\r//' $(VENDOR_SDK_DIR)/ld/eagle.app.v6.ld | sed -e s@../ld/@@ >$(TOOLCHAIN)/xtensa-lx106-elf/usr/lib/eagle.app.v6.ld
+	@sed -e 's/\r//' $(VENDOR_SDK_DIR)/ld/eagle.rom.addr.v6.ld >$(TOOLCHAIN)/xtensa-lx106-elf/usr/lib/eagle.rom.addr.v6.ld
+else
+	cp -Rf $(VENDOR_SDK_DIR) $(TOP)/$(VENDOR_SDK_DIR)
+	rm -f $(TOP)/$(VENDOR_SDK_DIR)/lib/libgcc.a
+	rm -f $(TOP)/$(VENDOR_SDK_DIR)/lib/libc.a
+	ln -snf $(TOP)/$(VENDOR_SDK_DIR) $(TOP)/sdk
+endif
 
-$(VENDOR_SDK_DIR)/.dir: $(VENDOR_SDK_ZIP)
-	$(UNZIP) $^
+postbuild:
+	@echo "Installing vendor SDK headers into sysroot"
+	@cp -f sdk/include/c_types.h $(TOOLCHAIN)/xtensa-lx106-elf/sys-include/
+	@cp -f $(TOP)/esp-open-lwip/include/lwipopts.h $(TOOLCHAIN)/xtensa-lx106-elf/sys-include/
+	@cp -Rf $(TOOLCHAIN)/xtensa-lx106-elf/usr/include/lwip $(TOOLCHAIN)/xtensa-lx106-elf/sys-include/
+	@cp -Rf $(TOOLCHAIN)/xtensa-lx106-elf/usr/include/arch $(TOOLCHAIN)/xtensa-lx106-elf/sys-include/
+	@cp -Rf $(TOOLCHAIN)/xtensa-lx106-elf/usr/include/xtensa/* $(TOOLCHAIN)/xtensa-lx106-elf/sys-include/xtensa/
+	@echo "Installing vendor SDK libs into sysroot"
+	@cp -f $(TOOLCHAIN)/xtensa-lx106-elf/usr/lib/libhal.a $(TOOLCHAIN)/xtensa-lx106-elf/lib/libhal.a
+
+clean-sdk-build:
+	rm -f .sdk_dir_$(VENDOR_SDK) .sdk_patch_$(VENDOR_SDK)
+	$(shell [[ -L sdk ]] && unlink sdk)
+	rm -f $(VENDOR_GIT_ZIP)
+	rm -rf $(VENDOR_SDK_DIR)
+
+clean: clean-sdk-build
+	rm -f .sdk_patch_$(VENDOR_SDK)
+	rm -f user_rf_cal_sector_set.o empty_user_rf_pre_init.o
+	$(MAKE) -C esp-open-lwip -f Makefile.open clean
+	rm -f .sdk_dir_$(VENDOR_SDK)
+
+distclean: clean
+	$(MAKE) -C crosstool-ng clean MAKELEVEL=0
+	-rm -f crosstool-ng/.config.org
+	-rm -rf crosstool-ng/lib
+	-rm -rf crosstool-ng/share
+	-rm -rf crosstool-ng/.build/src
+	-rm -rf $(TOOLCHAIN)
+
+empty_user_rf_pre_init.o: empty_user_rf_pre_init.c $(TOOLCHAIN)/bin/xtensa-lx106-elf-gcc $(VENDOR_SDK_DIR)
+	$(TOOLCHAIN)/bin/xtensa-lx106-elf-gcc -O2 -I$(VENDOR_SDK_DIR)/include -c $<
+
+user_rf_cal_sector_set.o: user_rf_cal_sector_set.c $(TOOLCHAIN)/bin/xtensa-lx106-elf-gcc $(VENDOR_SDK_DIR)
+	$(TOOLCHAIN)/bin/xtensa-lx106-elf-gcc -O2 -I$(VENDOR_SDK_DIR)/include -c $<
+
+.sdk_dir_$(VENDOR_SDK): $(VENDOR_SDK_ZIP)
+	-mv -f $(VENDOR_ZIP_DIR) $(VENDOR_SDK_DIR)
 	-mv License $(VENDOR_SDK_DIR)
-	touch $@
+	@touch $@
 
-$(VENDOR_SDK_DIR_2.1.0-18-g61248df)/.dir:
-	echo $(VENDOR_SDK_DIR_2.1.0-18-g61248df)
-	git clone https://github.com/espressif/ESP8266_NONOS_SDK $(VENDOR_SDK_DIR_2.1.0-18-g61248df)
-	(cd $(VENDOR_SDK_DIR_2.1.0-18-g61248df); git checkout 61248df5f6)
-	touch $@
-
-$(VENDOR_SDK_DIR_2.1.0)/.dir: $(VENDOR_SDK_ZIP_2.1.0)
-	$(UNZIP) $^
-	touch $@
-
-$(VENDOR_SDK_DIR_2.0.0)/.dir: $(VENDOR_SDK_ZIP_2.0.0)
-	$(UNZIP) $^
-	mv ESP8266_NONOS_SDK $(VENDOR_SDK_DIR_2.0.0)
-	-mv License $(VENDOR_SDK_DIR)
-	touch $@
-
-$(VENDOR_SDK_DIR_1.5.4)/.dir: $(VENDOR_SDK_ZIP_1.5.4)
-	$(UNZIP) $^
-	mv ESP8266_NONOS_SDK $(VENDOR_SDK_DIR_1.5.4)
-	-mv License $(VENDOR_SDK_DIR)
-	touch $@
-
-sdk_patch: $(VENDOR_SDK_DIR)/.dir .sdk_patch_$(VENDOR_SDK)
-
-.sdk_patch_2.1.0-18-g61248df .sdk_patch_2.1.0: user_rf_cal_sector_set.o
+.sdk_patch_master: user_rf_cal_sector_set.o
 	echo -e "#undef ESP_SDK_VERSION\n#define ESP_SDK_VERSION 020100" >>$(VENDOR_SDK_DIR)/include/esp_sdk_ver.h
 	$(PATCH) -d $(VENDOR_SDK_DIR) -p1 < c_types-c99_sdk_2.patch
 	cd $(VENDOR_SDK_DIR)/lib; mkdir -p tmp; cd tmp; $(TOOLCHAIN)/bin/xtensa-lx106-elf-ar x ../libcrypto.a; cd ..; $(TOOLCHAIN)/bin/xtensa-lx106-elf-ar rs libwpa.a tmp/*.o
@@ -342,29 +400,23 @@ sdk_patch: $(VENDOR_SDK_DIR)/.dir .sdk_patch_$(VENDOR_SDK)
 	$(UNZIP) $<
 	@touch $@
 
-.sdk_patch_0.9.2: FRM_ERR_PATCH.rar esp_iot_sdk_v0.9.2/.dir 
+.sdk_patch_0.9.2: FRM_ERR_PATCH.rar esp_iot_sdk_v0.9.2/.dir
 	unrar x -o+ $<
 	cp FRM_ERR_PATCH/*.a $(VENDOR_SDK_DIR)/lib/
 	@touch $@
 
-empty_user_rf_pre_init.o: empty_user_rf_pre_init.c $(TOOLCHAIN)/bin/xtensa-lx106-elf-gcc $(VENDOR_SDK_DIR)/.dir
-	$(TOOLCHAIN)/bin/xtensa-lx106-elf-gcc -O2 -I$(VENDOR_SDK_DIR)/include -c $<
-
-user_rf_cal_sector_set.o: user_rf_cal_sector_set.c $(TOOLCHAIN)/bin/xtensa-lx106-elf-gcc $(VENDOR_SDK_DIR)/.dir
-	$(TOOLCHAIN)/bin/xtensa-lx106-elf-gcc -O2 -I$(VENDOR_SDK_DIR)/include -c $<
-
-lwip: toolchain sdk_patch
-ifeq ($(STANDALONE),y)
-	$(MAKE) -C esp-open-lwip -f Makefile.open install \
-	    CC=$(TOOLCHAIN)/bin/xtensa-lx106-elf-gcc \
-	    AR=$(TOOLCHAIN)/bin/xtensa-lx106-elf-ar \
-	    PREFIX=$(TOOLCHAIN)
-	cp -a esp-open-lwip/include/arch esp-open-lwip/include/lwip esp-open-lwip/include/netif \
-	    esp-open-lwip/include/lwipopts.h \
-	    $(TOOLCHAIN)/xtensa-lx106-elf/sysroot/usr/include/
-endif
-
+#######################################################################################################
+# Presumes VENDOR_FULL_SHA is >= the SDK version
+#######################################################################################################
+ESP8266_NONOS_SDK-master.zip:
+	wget --content-disposition "$(VENDOR_ZIP_DL_URI)"
+	rm -rf 'ESP8266_NONOS_SDK-master/*'
+	mkdir -p 'ESP8266_NONOS_SDK-master'
+	unzip $(VENDOR_GIT_ZIP)
+	cp -a ESP8266_NONOS_SDK-$(VENDOR_FULL_SHA)/* ESP8266_NONOS_SDK-master/
+	rm -rf ESP8266_NONOS_SDK-$(VENDOR_FULL_SHA)
 
+#######################################################################################################
 ESP8266_NONOS_SDK-2.1.0.zip:
 	wget --content-disposition "https://github.com/espressif/ESP8266_NONOS_SDK/archive/v2.1.0.zip"
 # The only change wrt to ESP8266_NONOS_SDK_V2.0.0_16_07_19.zip is licensing blurb in source/
diff --git a/strip_libc_funcs.txt b/strip_libc_funcs.txt
new file mode 100644
index 0000000..db4e6b2
--- /dev/null
+++ b/strip_libc_funcs.txt
@@ -0,0 +1,15 @@
+OPEN libc.a
+DELETE lib_a-bzero.o
+DELETE lib_a-memcmp.o
+DELETE lib_a-memcpy.o
+DELETE lib_a-memmove.o
+DELETE lib_a-memset.o
+DELETE lib_a-rand.o
+DELETE lib_a-strcmp.o
+DELETE lib_a-strcpy.o
+DELETE lib_a-strlen.o
+DELETE lib_a-strncmp.o
+DELETE lib_a-strncpy.o
+DELETE lib_a-strstr.o
+SAVE
+END
\ No newline at end of file
diff --git a/strip_libgcc_funcs.txt b/strip_libgcc_funcs.txt
new file mode 100644
index 0000000..ab9b506
--- /dev/null
+++ b/strip_libgcc_funcs.txt
@@ -0,0 +1,25 @@
+OPEN libgcc.a
+DELETE _addsubdf3.o
+DELETE _addsubsf3.o
+DELETE _divdf3.o
+DELETE _divdi3.o
+DELETE _divsi3.o
+DELETE _extendsfdf2.o
+DELETE _fixdfsi.o
+DELETE _fixunsdfsi.o
+DELETE _fixunssfsi.o
+DELETE _floatsidf.o
+DELETE _floatsisf.o
+DELETE _floatunsidf.o
+DELETE _floatunsisf.o
+DELETE _muldf3.o
+DELETE _muldi3.o
+DELETE _mulsf3.o
+DELETE _truncdfsf2.o
+DELETE _udivdi3.o
+DELETE _udivsi3.o
+DELETE _umoddi3.o
+DELETE _umodsi3.o
+DELETE _umulsidi3.o
+SAVE
+END
\ No newline at end of file
diff --git a/user_rf_cal_sector_set.c b/user_rf_cal_sector_set.c
index 0dc4fd3..915fe61 100644
--- a/user_rf_cal_sector_set.c
+++ b/user_rf_cal_sector_set.c
@@ -1,6 +1,7 @@
 #include <c_types.h>
 #include <spi_flash.h>
 
+__attribute__ ((weak))
 uint32 user_rf_cal_sector_set(void) {
     extern char flashchip;
     SpiFlashChip *flash = (SpiFlashChip*)(&flashchip + 4);
@@ -9,3 +10,4 @@ uint32 user_rf_cal_sector_set(void) {
     uint32_t sec_num = flash->chip_size >> 12;
     return sec_num - 5;
 }
+