diff --git a/variants/arduino_zero/build_gcc/Makefile b/variants/arduino_zero/build_gcc/Makefile
deleted file mode 100644
index 841a76884d47d09eb12928995cdd63b454e8f8b3..0000000000000000000000000000000000000000
--- a/variants/arduino_zero/build_gcc/Makefile
+++ /dev/null
@@ -1,42 +0,0 @@
-#
-#  Copyright (c) 2014 Arduino.  All right reserved.
-#
-#  This library is free software; you can redistribute it and/or
-#  modify it under the terms of the GNU Lesser General Public
-#  License as published by the Free Software Foundation; either
-#  version 2.1 of the License, or (at your option) any later version.
-#
-#  This library is distributed in the hope that it will be useful,
-#  but WITHOUT ANY WARRANTY; without even the implied warranty of
-#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
-#  See the GNU Lesser General Public License for more details.
-#
-#  You should have received a copy of the GNU Lesser General Public
-#  License along with this library; if not, write to the Free Software
-#  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
-#
-
-SUBMAKE_OPTIONS=--no-builtin-rules --no-builtin-variables --no-print-directory
-
-#-------------------------------------------------------------------------------
-# Rules
-#-------------------------------------------------------------------------------
-
-all: arduino_zero
-
-.PHONY: arduino_zero
-samd21_xpro:
-	@echo ------------------------------------------------------------------------------------
-	@echo --- Making variant arduino_zero
-	@$(MAKE) DEBUG=1 $(SUBMAKE_OPTIONS) -f libvariant_arduino_zero.mk
-#	@$(MAKE) $(SUBMAKE_OPTIONS) -f libvariant_arduino_zero.mk
-	@echo ------------------------------------------------------------------------------------
-
-.PHONY: clean
-clean:
-	@echo ------------------------------------------------------------------------------------
-	@echo --- Cleaning variant arduino_due_x
-	@$(MAKE) DEBUG=1 $(SUBMAKE_OPTIONS) -f libvariant_arduino_zero.mk $@
-#	@$(MAKE) $(SUBMAKE_OPTIONS) -f libvariant_arduino_zero.mk $@
-	@echo ------------------------------------------------------------------------------------
-
diff --git a/variants/arduino_zero/build_gcc/debug.mk b/variants/arduino_zero/build_gcc/debug.mk
deleted file mode 100644
index 5f3e4e0463ee2191a9a08e734f415b66fba767a2..0000000000000000000000000000000000000000
--- a/variants/arduino_zero/build_gcc/debug.mk
+++ /dev/null
@@ -1,25 +0,0 @@
-#
-#  Copyright (c) 2014 Arduino.  All right reserved.
-#
-#  This library is free software; you can redistribute it and/or
-#  modify it under the terms of the GNU Lesser General Public
-#  License as published by the Free Software Foundation; either
-#  version 2.1 of the License, or (at your option) any later version.
-#
-#  This library is distributed in the hope that it will be useful,
-#  but WITHOUT ANY WARRANTY; without even the implied warranty of
-#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
-#  See the GNU Lesser General Public License for more details.
-#
-#  You should have received a copy of the GNU Lesser General Public
-#  License along with this library; if not, write to the Free Software
-#  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
-#
-
-# Optimization level
-# -O1 Optimize
-# -O2 Optimize even more
-# -O3 Optimize yet more
-# -O0 Reduce compilation time and make debugging produce the expected results
-# -Os Optimize for size
-OPTIMIZATION = -g -O0 -DDEBUG
diff --git a/variants/arduino_zero/build_gcc/gcc.mk b/variants/arduino_zero/build_gcc/gcc.mk
deleted file mode 100644
index 7c67fecf469e6f41c711883073593c2f12f681d5..0000000000000000000000000000000000000000
--- a/variants/arduino_zero/build_gcc/gcc.mk
+++ /dev/null
@@ -1,82 +0,0 @@
-#
-#  Copyright (c) 2014 Arduino.  All right reserved.
-#
-#  This library is free software; you can redistribute it and/or
-#  modify it under the terms of the GNU Lesser General Public
-#  License as published by the Free Software Foundation; either
-#  version 2.1 of the License, or (at your option) any later version.
-#
-#  This library is distributed in the hope that it will be useful,
-#  but WITHOUT ANY WARRANTY; without even the implied warranty of
-#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
-#  See the GNU Lesser General Public License for more details.
-#
-#  You should have received a copy of the GNU Lesser General Public
-#  License along with this library; if not, write to the Free Software
-#  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
-#
-
-# Tool suffix when cross-compiling
-CROSS_COMPILE = $(ARM_GCC_TOOLCHAIN)/arm-none-eabi-
-
-# Compilation tools
-AR = $(CROSS_COMPILE)ar
-CC = $(CROSS_COMPILE)gcc
-CXX = $(CROSS_COMPILE)g++
-AS = $(CROSS_COMPILE)as
-NM = $(CROSS_COMPILE)nm
-ifeq ($(OS),Windows_NT)
-RM=cs-rm -Rf
-else
-RM=rm -Rf
-endif
-
-SEP=\\
-
-# ---------------------------------------------------------------------------------------
-# C Flags
-
-CFLAGS += -Wall -Wchar-subscripts -Wcomment -Wformat=2 -Wimplicit-int
-CFLAGS += -Werror-implicit-function-declaration -Wmain -Wparentheses
-CFLAGS += -Wsequence-point -Wreturn-type -Wswitch -Wtrigraphs -Wunused
-CFLAGS += -Wuninitialized -Wunknown-pragmas -Wfloat-equal -Wundef
-CFLAGS += -Wshadow -Wpointer-arith -Wbad-function-cast -Wwrite-strings
-CFLAGS += -Wsign-compare -Waggregate-return -Wstrict-prototypes
-CFLAGS += -Wmissing-prototypes -Wmissing-declarations
-CFLAGS += -Wformat -Wmissing-format-attribute -Wno-deprecated-declarations
-CFLAGS += -Wpacked -Wredundant-decls -Wnested-externs -Winline -Wlong-long
-CFLAGS += -Wunreachable-code
-CFLAGS += -Wcast-align
-#CFLAGS += -Wmissing-noreturn
-#CFLAGS += -Wconversion
-
-CFLAGS += --param max-inline-insns-single=500 -mcpu=cortex-m0p -mthumb -mlong-calls -ffunction-sections -fdata-sections -nostdlib -std=c99
-CFLAGS += $(OPTIMIZATION) $(INCLUDES) -D$(CHIP) -D$(VARIANT)
-
-# To reduce application size use only integer printf function.
-CFLAGS += -Dprintf=iprintf
-
-# ---------------------------------------------------------------------------------------
-# CPP Flags
-
-CPPFLAGS += -Wall -Wchar-subscripts -Wcomment -Wformat=2
-CPPFLAGS += -Wmain -Wparentheses -Wcast-align -Wunreachable-code
-CPPFLAGS += -Wsequence-point -Wreturn-type -Wswitch -Wtrigraphs -Wunused
-CPPFLAGS += -Wuninitialized -Wunknown-pragmas -Wfloat-equal -Wundef
-CPPFLAGS += -Wshadow -Wpointer-arith -Wwrite-strings
-CPPFLAGS += -Wsign-compare -Waggregate-return -Wmissing-declarations
-CPPFLAGS += -Wformat -Wmissing-format-attribute -Wno-deprecated-declarations
-CPPFLAGS += -Wpacked -Wredundant-decls -Winline -Wlong-long
-#CPPFLAGS += -Wmissing-noreturn
-#CPPFLAGS += -Wconversion
-
-CPPFLAGS += --param max-inline-insns-single=500 -mcpu=cortex-m0p -mthumb -mlong-calls -ffunction-sections -fdata-sections -fno-rtti -fno-exceptions -std=c++98
-CPPFLAGS += $(OPTIMIZATION) $(INCLUDES) -D$(CHIP)
-
-# To reduce application size use only integer printf function.
-CPPFLAGS += -Dprintf=iprintf
-
-# ---------------------------------------------------------------------------------------
-# ASM Flags
-
-ASFLAGS = -mcpu=cortex-m0p -mthumb -Wall -g $(OPTIMIZATION) $(INCLUDES)
diff --git a/variants/arduino_zero/build_gcc/libvariant_arduino_zero.mk b/variants/arduino_zero/build_gcc/libvariant_arduino_zero.mk
deleted file mode 100644
index 91ebe38e8affeb9ea6af45282cb48dbebd059d97..0000000000000000000000000000000000000000
--- a/variants/arduino_zero/build_gcc/libvariant_arduino_zero.mk
+++ /dev/null
@@ -1,184 +0,0 @@
-#
-#  Copyright (c) 2014 Arduino.  All right reserved.
-#
-#  This library is free software; you can redistribute it and/or
-#  modify it under the terms of the GNU Lesser General Public
-#  License as published by the Free Software Foundation; either
-#  version 2.1 of the License, or (at your option) any later version.
-#
-#  This library is distributed in the hope that it will be useful,
-#  but WITHOUT ANY WARRANTY; without even the implied warranty of
-#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
-#  See the GNU Lesser General Public License for more details.
-#
-#  You should have received a copy of the GNU Lesser General Public
-#  License along with this library; if not, write to the Free Software
-#  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
-#
-
-# Makefile for compiling libArduino
-.SUFFIXES: .o .a .c .s
-
-CHIP=__SAMD21G18A__
-VARIANT=arduino_zero
-LIBNAME=libvariant_$(VARIANT)
-TOOLCHAIN=gcc
-
-#-------------------------------------------------------------------------------
-# Path
-#-------------------------------------------------------------------------------
-
-# Output directories
-OUTPUT_BIN = ../../../cores/arduino
-
-# Libraries
-PROJECT_BASE_PATH = ..
-SYSTEM_PATH = ../../../system
-CMSIS_ROOT_PATH = $(SYSTEM_PATH)/CMSIS
-CMSIS_ARM_PATH=$(CMSIS_ROOT_PATH)/CMSIS/Include
-CMSIS_ATMEL_PATH=$(CMSIS_ROOT_PATH)/Device/ATMEL
-#CMSIS_CHIP_PATH=$(CMSIS_ROOT_PATH)/Device/ATMEL/$(CHIP_SERIE)
-
-ARDUINO_PATH = ../../../cores/arduino
-VARIANT_BASE_PATH = ../../../variants
-VARIANT_PATH = ../../../variants/$(VARIANT)
-
-#-------------------------------------------------------------------------------
-# Files
-#-------------------------------------------------------------------------------
-
-#vpath %.h $(PROJECT_BASE_PATH) $(SYSTEM_PATH) $(VARIANT_PATH)
-vpath %.cpp $(PROJECT_BASE_PATH)
-
-VPATH+=$(PROJECT_BASE_PATH)
-
-INCLUDES =
-#INCLUDES += -I$(PROJECT_BASE_PATH)
-INCLUDES += -I$(ARDUINO_PATH)
-INCLUDES += -I$(ARDUINO_PATH)/USB
-INCLUDES += -I$(SYSTEM_PATH)
-INCLUDES += -I$(SYSTEM_PATH)/libsamd
-INCLUDES += -I$(SYSTEM_PATH)/USBHost
-INCLUDES += -I$(VARIANT_BASE_PATH)
-INCLUDES += -I$(VARIANT_PATH)
-INCLUDES += -I$(CMSIS_ARM_PATH)
-INCLUDES += -I$(CMSIS_ATMEL_PATH)
-
-#-------------------------------------------------------------------------------
-ifdef DEBUG
-include debug.mk
-else
-include release.mk
-endif
-
-#-------------------------------------------------------------------------------
-# Tools
-#-------------------------------------------------------------------------------
-
-include $(TOOLCHAIN).mk
-
-#-------------------------------------------------------------------------------
-ifdef DEBUG
-OUTPUT_OBJ=debug
-OUTPUT_LIB_POSTFIX=dbg
-else
-OUTPUT_OBJ=release
-OUTPUT_LIB_POSTFIX=rel
-endif
-
-OUTPUT_LIB=$(LIBNAME)_$(TOOLCHAIN)_$(OUTPUT_LIB_POSTFIX).a
-OUTPUT_PATH=$(OUTPUT_OBJ)_$(VARIANT)
-
-#-------------------------------------------------------------------------------
-# C source files and objects
-#-------------------------------------------------------------------------------
-C_SRC=$(wildcard $(PROJECT_BASE_PATH)/*.c)
-
-C_OBJ_TEMP = $(patsubst %.c, %.o, $(notdir $(C_SRC)))
-
-# during development, remove some files
-C_OBJ_FILTER=
-
-C_OBJ=$(filter-out $(C_OBJ_FILTER), $(C_OBJ_TEMP))
-
-#-------------------------------------------------------------------------------
-# CPP source files and objects
-#-------------------------------------------------------------------------------
-CPP_SRC=$(wildcard $(PROJECT_BASE_PATH)/*.cpp)
-
-CPP_OBJ_TEMP = $(patsubst %.cpp, %.o, $(notdir $(CPP_SRC)))
-
-# during development, remove some files
-CPP_OBJ_FILTER=
-
-CPP_OBJ=$(filter-out $(CPP_OBJ_FILTER), $(CPP_OBJ_TEMP))
-
-#-------------------------------------------------------------------------------
-# Assembler source files and objects
-#-------------------------------------------------------------------------------
-A_SRC=$(wildcard $(PROJECT_BASE_PATH)/*.s)
-
-A_OBJ_TEMP=$(patsubst %.s, %.o, $(notdir $(A_SRC)))
-
-# during development, remove some files
-A_OBJ_FILTER=
-
-A_OBJ=$(filter-out $(A_OBJ_FILTER), $(A_OBJ_TEMP))
-
-#-------------------------------------------------------------------------------
-# Rules
-#-------------------------------------------------------------------------------
-all: $(VARIANT)
-
-$(VARIANT): create_output $(OUTPUT_LIB)
-
-.PHONY: create_output
-create_output:
-	@echo ------------------------------------------------------------------------------------
-	@echo -------------------------
-	@echo --- Preparing variant $(VARIANT) files in $(OUTPUT_PATH) $(OUTPUT_BIN)
-	@echo -------------------------
-#	@echo *$(INCLUDES)
-#	@echo -------------------------
-#	@echo *$(C_SRC)
-#	@echo -------------------------
-#	@echo *$(C_OBJ)
-#	@echo -------------------------
-#	@echo *$(addprefix $(OUTPUT_PATH)/, $(C_OBJ))
-#	@echo -------------------------
-#	@echo *$(CPP_SRC)
-#	@echo -------------------------
-#	@echo *$(CPP_OBJ)
-#	@echo -------------------------
-#	@echo *$(addprefix $(OUTPUT_PATH)/, $(CPP_OBJ))
-#	@echo -------------------------
-#	@echo *$(A_SRC)
-#	@echo -------------------------
-
-	-@mkdir $(OUTPUT_PATH) 1>NUL 2>&1
-	@echo ------------------------------------------------------------------------------------
-
-$(addprefix $(OUTPUT_PATH)/,$(C_OBJ)): $(OUTPUT_PATH)/%.o: %.c
-#	@"$(CC)" -v -c $(CFLAGS) $< -o $@
-	@"$(CC)" -c $(CFLAGS) $< -o $@
-
-$(addprefix $(OUTPUT_PATH)/,$(CPP_OBJ)): $(OUTPUT_PATH)/%.o: %.cpp
-#	@"$(CC)" -c $(CPPFLAGS) $< -o $@
-	@"$(CC)" -xc++ -c $(CPPFLAGS) $< -o $@
-
-$(addprefix $(OUTPUT_PATH)/,$(A_OBJ)): $(OUTPUT_PATH)/%.o: %.s
-	@"$(AS)" -c $(ASFLAGS) $< -o $@
-
-$(OUTPUT_LIB): $(addprefix $(OUTPUT_PATH)/, $(C_OBJ)) $(addprefix $(OUTPUT_PATH)/, $(CPP_OBJ)) $(addprefix $(OUTPUT_PATH)/, $(A_OBJ))
-	@"$(AR)" -v -r "$(OUTPUT_BIN)/$@" $^
-	@"$(NM)" "$(OUTPUT_BIN)/$@" > "$(OUTPUT_BIN)/$@.txt"
-
-
-.PHONY: clean
-clean:
-	@echo ------------------------------------------------------------------------------------
-	@echo --- Cleaning $(VARIANT) files [$(OUTPUT_PATH)$(SEP)*.o]
-	-@$(RM) $(OUTPUT_PATH) 1>NUL 2>&1
-	-@$(RM) $(OUTPUT_BIN)/$(OUTPUT_LIB) 1>NUL 2>&1
-	@echo ------------------------------------------------------------------------------------
-
diff --git a/variants/arduino_zero/build_gcc/release.mk b/variants/arduino_zero/build_gcc/release.mk
deleted file mode 100644
index 0d15157f4f7f9a167d11b351dec063a2b8229896..0000000000000000000000000000000000000000
--- a/variants/arduino_zero/build_gcc/release.mk
+++ /dev/null
@@ -1,25 +0,0 @@
-#
-#  Copyright (c) 2011 Arduino.  All right reserved.
-#
-#  This library is free software; you can redistribute it and/or
-#  modify it under the terms of the GNU Lesser General Public
-#  License as published by the Free Software Foundation; either
-#  version 2.1 of the License, or (at your option) any later version.
-#
-#  This library is distributed in the hope that it will be useful,
-#  but WITHOUT ANY WARRANTY; without even the implied warranty of
-#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 
-#  See the GNU Lesser General Public License for more details.
-#
-#  You should have received a copy of the GNU Lesser General Public
-#  License along with this library; if not, write to the Free Software
-#  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
-#
-
-# Optimization level
-# -O1 Optimize
-# -O2 Optimize even more
-# -O3 Optimize yet more
-# -O0 Reduce compilation time and make debugging produce the expected results
-# -Os Optimize for size
-OPTIMIZATION = -Os
diff --git a/variants/samd21_xpro/build_gcc/Makefile b/variants/samd21_xpro/build_gcc/Makefile
deleted file mode 100644
index dfbbcb935c9d2d37101ea413df51a484cadff236..0000000000000000000000000000000000000000
--- a/variants/samd21_xpro/build_gcc/Makefile
+++ /dev/null
@@ -1,42 +0,0 @@
-#
-#  Copyright (c) 2014 Arduino.  All right reserved.
-#
-#  This library is free software; you can redistribute it and/or
-#  modify it under the terms of the GNU Lesser General Public
-#  License as published by the Free Software Foundation; either
-#  version 2.1 of the License, or (at your option) any later version.
-#
-#  This library is distributed in the hope that it will be useful,
-#  but WITHOUT ANY WARRANTY; without even the implied warranty of
-#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
-#  See the GNU Lesser General Public License for more details.
-#
-#  You should have received a copy of the GNU Lesser General Public
-#  License along with this library; if not, write to the Free Software
-#  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
-#
-
-SUBMAKE_OPTIONS=--no-builtin-rules --no-builtin-variables --no-print-directory
-
-#-------------------------------------------------------------------------------
-# Rules
-#-------------------------------------------------------------------------------
-
-all: samd21_xpro
-
-.PHONY: samd21_xpro
-samd21_xpro:
-	@echo ------------------------------------------------------------------------------------
-	@echo --- Making variant samd21_xpro
-	@$(MAKE) DEBUG=1 $(SUBMAKE_OPTIONS) -f libvariant_samd21_xpro.mk
-#	@$(MAKE) $(SUBMAKE_OPTIONS) -f libvariant_samd21_xpro.mk
-	@echo ------------------------------------------------------------------------------------
-
-.PHONY: clean
-clean:
-	@echo ------------------------------------------------------------------------------------
-	@echo --- Cleaning variant arduino_due_x
-	@$(MAKE) DEBUG=1 $(SUBMAKE_OPTIONS) -f libvariant_samd21_xpro.mk $@
-#	@$(MAKE) $(SUBMAKE_OPTIONS) -f libvariant_samd21_xpro.mk $@
-	@echo ------------------------------------------------------------------------------------
-
diff --git a/variants/samd21_xpro/build_gcc/debug.mk b/variants/samd21_xpro/build_gcc/debug.mk
deleted file mode 100644
index 5f3e4e0463ee2191a9a08e734f415b66fba767a2..0000000000000000000000000000000000000000
--- a/variants/samd21_xpro/build_gcc/debug.mk
+++ /dev/null
@@ -1,25 +0,0 @@
-#
-#  Copyright (c) 2014 Arduino.  All right reserved.
-#
-#  This library is free software; you can redistribute it and/or
-#  modify it under the terms of the GNU Lesser General Public
-#  License as published by the Free Software Foundation; either
-#  version 2.1 of the License, or (at your option) any later version.
-#
-#  This library is distributed in the hope that it will be useful,
-#  but WITHOUT ANY WARRANTY; without even the implied warranty of
-#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
-#  See the GNU Lesser General Public License for more details.
-#
-#  You should have received a copy of the GNU Lesser General Public
-#  License along with this library; if not, write to the Free Software
-#  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
-#
-
-# Optimization level
-# -O1 Optimize
-# -O2 Optimize even more
-# -O3 Optimize yet more
-# -O0 Reduce compilation time and make debugging produce the expected results
-# -Os Optimize for size
-OPTIMIZATION = -g -O0 -DDEBUG
diff --git a/variants/samd21_xpro/build_gcc/gcc.mk b/variants/samd21_xpro/build_gcc/gcc.mk
deleted file mode 100644
index 7c67fecf469e6f41c711883073593c2f12f681d5..0000000000000000000000000000000000000000
--- a/variants/samd21_xpro/build_gcc/gcc.mk
+++ /dev/null
@@ -1,82 +0,0 @@
-#
-#  Copyright (c) 2014 Arduino.  All right reserved.
-#
-#  This library is free software; you can redistribute it and/or
-#  modify it under the terms of the GNU Lesser General Public
-#  License as published by the Free Software Foundation; either
-#  version 2.1 of the License, or (at your option) any later version.
-#
-#  This library is distributed in the hope that it will be useful,
-#  but WITHOUT ANY WARRANTY; without even the implied warranty of
-#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
-#  See the GNU Lesser General Public License for more details.
-#
-#  You should have received a copy of the GNU Lesser General Public
-#  License along with this library; if not, write to the Free Software
-#  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
-#
-
-# Tool suffix when cross-compiling
-CROSS_COMPILE = $(ARM_GCC_TOOLCHAIN)/arm-none-eabi-
-
-# Compilation tools
-AR = $(CROSS_COMPILE)ar
-CC = $(CROSS_COMPILE)gcc
-CXX = $(CROSS_COMPILE)g++
-AS = $(CROSS_COMPILE)as
-NM = $(CROSS_COMPILE)nm
-ifeq ($(OS),Windows_NT)
-RM=cs-rm -Rf
-else
-RM=rm -Rf
-endif
-
-SEP=\\
-
-# ---------------------------------------------------------------------------------------
-# C Flags
-
-CFLAGS += -Wall -Wchar-subscripts -Wcomment -Wformat=2 -Wimplicit-int
-CFLAGS += -Werror-implicit-function-declaration -Wmain -Wparentheses
-CFLAGS += -Wsequence-point -Wreturn-type -Wswitch -Wtrigraphs -Wunused
-CFLAGS += -Wuninitialized -Wunknown-pragmas -Wfloat-equal -Wundef
-CFLAGS += -Wshadow -Wpointer-arith -Wbad-function-cast -Wwrite-strings
-CFLAGS += -Wsign-compare -Waggregate-return -Wstrict-prototypes
-CFLAGS += -Wmissing-prototypes -Wmissing-declarations
-CFLAGS += -Wformat -Wmissing-format-attribute -Wno-deprecated-declarations
-CFLAGS += -Wpacked -Wredundant-decls -Wnested-externs -Winline -Wlong-long
-CFLAGS += -Wunreachable-code
-CFLAGS += -Wcast-align
-#CFLAGS += -Wmissing-noreturn
-#CFLAGS += -Wconversion
-
-CFLAGS += --param max-inline-insns-single=500 -mcpu=cortex-m0p -mthumb -mlong-calls -ffunction-sections -fdata-sections -nostdlib -std=c99
-CFLAGS += $(OPTIMIZATION) $(INCLUDES) -D$(CHIP) -D$(VARIANT)
-
-# To reduce application size use only integer printf function.
-CFLAGS += -Dprintf=iprintf
-
-# ---------------------------------------------------------------------------------------
-# CPP Flags
-
-CPPFLAGS += -Wall -Wchar-subscripts -Wcomment -Wformat=2
-CPPFLAGS += -Wmain -Wparentheses -Wcast-align -Wunreachable-code
-CPPFLAGS += -Wsequence-point -Wreturn-type -Wswitch -Wtrigraphs -Wunused
-CPPFLAGS += -Wuninitialized -Wunknown-pragmas -Wfloat-equal -Wundef
-CPPFLAGS += -Wshadow -Wpointer-arith -Wwrite-strings
-CPPFLAGS += -Wsign-compare -Waggregate-return -Wmissing-declarations
-CPPFLAGS += -Wformat -Wmissing-format-attribute -Wno-deprecated-declarations
-CPPFLAGS += -Wpacked -Wredundant-decls -Winline -Wlong-long
-#CPPFLAGS += -Wmissing-noreturn
-#CPPFLAGS += -Wconversion
-
-CPPFLAGS += --param max-inline-insns-single=500 -mcpu=cortex-m0p -mthumb -mlong-calls -ffunction-sections -fdata-sections -fno-rtti -fno-exceptions -std=c++98
-CPPFLAGS += $(OPTIMIZATION) $(INCLUDES) -D$(CHIP)
-
-# To reduce application size use only integer printf function.
-CPPFLAGS += -Dprintf=iprintf
-
-# ---------------------------------------------------------------------------------------
-# ASM Flags
-
-ASFLAGS = -mcpu=cortex-m0p -mthumb -Wall -g $(OPTIMIZATION) $(INCLUDES)
diff --git a/variants/samd21_xpro/build_gcc/libvariant_samd21_xpro.mk b/variants/samd21_xpro/build_gcc/libvariant_samd21_xpro.mk
deleted file mode 100644
index 042983062aedae334db83b7c73fb58f4282e0559..0000000000000000000000000000000000000000
--- a/variants/samd21_xpro/build_gcc/libvariant_samd21_xpro.mk
+++ /dev/null
@@ -1,184 +0,0 @@
-#
-#  Copyright (c) 2014 Arduino.  All right reserved.
-#
-#  This library is free software; you can redistribute it and/or
-#  modify it under the terms of the GNU Lesser General Public
-#  License as published by the Free Software Foundation; either
-#  version 2.1 of the License, or (at your option) any later version.
-#
-#  This library is distributed in the hope that it will be useful,
-#  but WITHOUT ANY WARRANTY; without even the implied warranty of
-#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
-#  See the GNU Lesser General Public License for more details.
-#
-#  You should have received a copy of the GNU Lesser General Public
-#  License along with this library; if not, write to the Free Software
-#  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
-#
-
-# Makefile for compiling libArduino
-.SUFFIXES: .o .a .c .s
-
-CHIP=__SAMD21J18A__
-VARIANT=samd21_xpro
-LIBNAME=libvariant_$(VARIANT)
-TOOLCHAIN=gcc
-
-#-------------------------------------------------------------------------------
-# Path
-#-------------------------------------------------------------------------------
-
-# Output directories
-OUTPUT_BIN = ../../../cores/arduino
-
-# Libraries
-PROJECT_BASE_PATH = ..
-SYSTEM_PATH = ../../../system
-CMSIS_ROOT_PATH = $(SYSTEM_PATH)/CMSIS
-CMSIS_ARM_PATH=$(CMSIS_ROOT_PATH)/CMSIS/Include
-CMSIS_ATMEL_PATH=$(CMSIS_ROOT_PATH)/Device/ATMEL
-#CMSIS_CHIP_PATH=$(CMSIS_ROOT_PATH)/Device/ATMEL/$(CHIP_SERIE)
-
-ARDUINO_PATH = ../../../cores/arduino
-VARIANT_BASE_PATH = ../../../variants
-VARIANT_PATH = ../../../variants/$(VARIANT)
-
-#-------------------------------------------------------------------------------
-# Files
-#-------------------------------------------------------------------------------
-
-#vpath %.h $(PROJECT_BASE_PATH) $(SYSTEM_PATH) $(VARIANT_PATH)
-vpath %.cpp $(PROJECT_BASE_PATH)
-
-VPATH+=$(PROJECT_BASE_PATH)
-
-INCLUDES =
-#INCLUDES += -I$(PROJECT_BASE_PATH)
-INCLUDES += -I$(ARDUINO_PATH)
-INCLUDES += -I$(ARDUINO_PATH)/USB
-INCLUDES += -I$(SYSTEM_PATH)
-INCLUDES += -I$(SYSTEM_PATH)/libsamd
-INCLUDES += -I$(SYSTEM_PATH)/USBHost
-INCLUDES += -I$(VARIANT_BASE_PATH)
-INCLUDES += -I$(VARIANT_PATH)
-INCLUDES += -I$(CMSIS_ARM_PATH)
-INCLUDES += -I$(CMSIS_ATMEL_PATH)
-
-#-------------------------------------------------------------------------------
-ifdef DEBUG
-include debug.mk
-else
-include release.mk
-endif
-
-#-------------------------------------------------------------------------------
-# Tools
-#-------------------------------------------------------------------------------
-
-include $(TOOLCHAIN).mk
-
-#-------------------------------------------------------------------------------
-ifdef DEBUG
-OUTPUT_OBJ=debug
-OUTPUT_LIB_POSTFIX=dbg
-else
-OUTPUT_OBJ=release
-OUTPUT_LIB_POSTFIX=rel
-endif
-
-OUTPUT_LIB=$(LIBNAME)_$(TOOLCHAIN)_$(OUTPUT_LIB_POSTFIX).a
-OUTPUT_PATH=$(OUTPUT_OBJ)_$(VARIANT)
-
-#-------------------------------------------------------------------------------
-# C source files and objects
-#-------------------------------------------------------------------------------
-C_SRC=$(wildcard $(PROJECT_BASE_PATH)/*.c)
-
-C_OBJ_TEMP = $(patsubst %.c, %.o, $(notdir $(C_SRC)))
-
-# during development, remove some files
-C_OBJ_FILTER=
-
-C_OBJ=$(filter-out $(C_OBJ_FILTER), $(C_OBJ_TEMP))
-
-#-------------------------------------------------------------------------------
-# CPP source files and objects
-#-------------------------------------------------------------------------------
-CPP_SRC=$(wildcard $(PROJECT_BASE_PATH)/*.cpp)
-
-CPP_OBJ_TEMP = $(patsubst %.cpp, %.o, $(notdir $(CPP_SRC)))
-
-# during development, remove some files
-CPP_OBJ_FILTER=
-
-CPP_OBJ=$(filter-out $(CPP_OBJ_FILTER), $(CPP_OBJ_TEMP))
-
-#-------------------------------------------------------------------------------
-# Assembler source files and objects
-#-------------------------------------------------------------------------------
-A_SRC=$(wildcard $(PROJECT_BASE_PATH)/*.s)
-
-A_OBJ_TEMP=$(patsubst %.s, %.o, $(notdir $(A_SRC)))
-
-# during development, remove some files
-A_OBJ_FILTER=
-
-A_OBJ=$(filter-out $(A_OBJ_FILTER), $(A_OBJ_TEMP))
-
-#-------------------------------------------------------------------------------
-# Rules
-#-------------------------------------------------------------------------------
-all: $(VARIANT)
-
-$(VARIANT): create_output $(OUTPUT_LIB)
-
-.PHONY: create_output
-create_output:
-	@echo ------------------------------------------------------------------------------------
-	@echo -------------------------
-	@echo --- Preparing variant $(VARIANT) files in $(OUTPUT_PATH) $(OUTPUT_BIN)
-	@echo -------------------------
-#	@echo *$(INCLUDES)
-#	@echo -------------------------
-#	@echo *$(C_SRC)
-#	@echo -------------------------
-#	@echo *$(C_OBJ)
-#	@echo -------------------------
-#	@echo *$(addprefix $(OUTPUT_PATH)/, $(C_OBJ))
-#	@echo -------------------------
-#	@echo *$(CPP_SRC)
-#	@echo -------------------------
-#	@echo *$(CPP_OBJ)
-#	@echo -------------------------
-#	@echo *$(addprefix $(OUTPUT_PATH)/, $(CPP_OBJ))
-#	@echo -------------------------
-#	@echo *$(A_SRC)
-#	@echo -------------------------
-
-	-@mkdir $(OUTPUT_PATH) 1>NUL 2>&1
-	@echo ------------------------------------------------------------------------------------
-
-$(addprefix $(OUTPUT_PATH)/,$(C_OBJ)): $(OUTPUT_PATH)/%.o: %.c
-#	@"$(CC)" -v -c $(CFLAGS) $< -o $@
-	@"$(CC)" -c $(CFLAGS) $< -o $@
-
-$(addprefix $(OUTPUT_PATH)/,$(CPP_OBJ)): $(OUTPUT_PATH)/%.o: %.cpp
-#	@"$(CC)" -c $(CPPFLAGS) $< -o $@
-	@"$(CC)" -xc++ -c $(CPPFLAGS) $< -o $@
-
-$(addprefix $(OUTPUT_PATH)/,$(A_OBJ)): $(OUTPUT_PATH)/%.o: %.s
-	@"$(AS)" -c $(ASFLAGS) $< -o $@
-
-$(OUTPUT_LIB): $(addprefix $(OUTPUT_PATH)/, $(C_OBJ)) $(addprefix $(OUTPUT_PATH)/, $(CPP_OBJ)) $(addprefix $(OUTPUT_PATH)/, $(A_OBJ))
-	@"$(AR)" -v -r "$(OUTPUT_BIN)/$@" $^
-	@"$(NM)" "$(OUTPUT_BIN)/$@" > "$(OUTPUT_BIN)/$@.txt"
-
-
-.PHONY: clean
-clean:
-	@echo ------------------------------------------------------------------------------------
-	@echo --- Cleaning $(VARIANT) files [$(OUTPUT_PATH)$(SEP)*.o]
-	-@$(RM) $(OUTPUT_PATH) 1>NUL 2>&1
-	-@$(RM) $(OUTPUT_BIN)/$(OUTPUT_LIB) 1>NUL 2>&1
-	@echo ------------------------------------------------------------------------------------
-
diff --git a/variants/samd21_xpro/build_gcc/release.mk b/variants/samd21_xpro/build_gcc/release.mk
deleted file mode 100644
index 0d15157f4f7f9a167d11b351dec063a2b8229896..0000000000000000000000000000000000000000
--- a/variants/samd21_xpro/build_gcc/release.mk
+++ /dev/null
@@ -1,25 +0,0 @@
-#
-#  Copyright (c) 2011 Arduino.  All right reserved.
-#
-#  This library is free software; you can redistribute it and/or
-#  modify it under the terms of the GNU Lesser General Public
-#  License as published by the Free Software Foundation; either
-#  version 2.1 of the License, or (at your option) any later version.
-#
-#  This library is distributed in the hope that it will be useful,
-#  but WITHOUT ANY WARRANTY; without even the implied warranty of
-#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 
-#  See the GNU Lesser General Public License for more details.
-#
-#  You should have received a copy of the GNU Lesser General Public
-#  License along with this library; if not, write to the Free Software
-#  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
-#
-
-# Optimization level
-# -O1 Optimize
-# -O2 Optimize even more
-# -O3 Optimize yet more
-# -O0 Reduce compilation time and make debugging produce the expected results
-# -Os Optimize for size
-OPTIMIZATION = -Os