diff --git a/configs/eagle100/README.txt b/configs/eagle100/README.txt
index 4182582bd2..36be863590 100644
--- a/configs/eagle100/README.txt
+++ b/configs/eagle100/README.txt
@@ -16,12 +16,34 @@ Development Environment
   environment because the Luminary FLASH programming application was used for
   writing to FLASH and this application works only under Windows.
 
-Toolchain
-^^^^^^^^^
+GNU Toolchain Options
+^^^^^^^^^^^^^^^^^^^^^
+
+  The NuttX make system has been modified to support the following different
+  toolchain options.
+
+  1. The CodeSourcery GNU toolchain,
+  2. The devkitARM GNU toolchain, or
+  3. The NuttX buildroot Toolchain (see below).
+
+  All testing has been conducted using the NuttX buildroot toolchain.  However,
+  the make system is setup to default to use the devkitARM toolchain.  To use
+  the CodeSource GNU toolchain, you simply need to build the system as follows:
+
+     make                         # Will build for the devkitARM toolchain
+     make CROSSDEV=arm-eabi-      # Will build for the devkitARM toolchain
+     make CROSSDEV=arm-none-eabi- # Will build for the CodeSourcery toolchain
+     make CROSSDEV=arm-elf-       # Will build for the NuttX buildroot toolchain
+
+  Of course, hard coding this CROSS_COMPILE value in Make.defs file will save
+  some repetitive typing.
+
+NuttX buildroot Toolchain
+^^^^^^^^^^^^^^^^^^^^^^^^^
 
   A GNU GCC-based toolchain is assumed.  The files */setenv.sh should
   be modified to point to the correct path to the Cortex-M3 GCC toolchain (if
-  different from the default).
+  different from the default in your PATH variable).
 
   If you have no Cortex-M3 toolchain, one can be downloaded from the NuttX
   SourceForge download site (https://sourceforge.net/project/showfiles.php?group_id=189573).
diff --git a/configs/eagle100/httpd/Make.defs b/configs/eagle100/httpd/Make.defs
index 393f936877..cf8e2e98df 100644
--- a/configs/eagle100/httpd/Make.defs
+++ b/configs/eagle100/httpd/Make.defs
@@ -35,7 +35,13 @@
 
 include ${TOPDIR}/.config
 
-CROSSDEV		= arm-elf-
+# The default value for CROSSDEV can be overridden from the make command line:
+#   make                         -- Will build for the devkitARM toolchain
+#   make CROSSDEV=arm-eabi-      -- Will build for the devkitARM toolchain
+#   make CROSSDEV=arm-none-eabi- -- Will build for the CodeSourcery toolchain
+#   make CROSSDEV=arm-elf-       -- Will build for the NuttX buildroot toolchain
+
+CROSSDEV		= arm-eabi-
 CC			= $(CROSSDEV)gcc
 CXX			= $(CROSSDEV)g++
 CPP			= $(CROSSDEV)gcc -E
@@ -59,7 +65,12 @@ else
   ARCHOPTIMIZATION	= -Os -fno-strict-aliasing -fno-strength-reduce -fomit-frame-pointer
 endif
 
-ARCHCPUFLAGS		= -mtune=cortex-m3 -march=armv7-m -mfloat-abi=soft
+ifeq ($(CROSSDEV),arm-elf-)
+  ARCHCPUFLAGS		= -mtune=cortex-m3 -march=armv7-m -mfloat-abi=soft
+else
+  ARCHCPUFLAGS		= -mcpu=cortex-m3 -mthumb -mfloat-abi=soft
+endif
+
 ARCHDEFINES		=
 ARCHINCLUDES		= -I. -isystem $(TOPDIR)/include
 ARCHXXINCLUDES		= -I. -isystem $(TOPDIR)/include -isystem $(TOPDIR)/include/cxx
@@ -78,7 +89,10 @@ OBJEXT			= .o
 LIBEXT			= .a
 EXEEXT			=
 
-ifeq ("${CONFIG_DEBUG}","y")
+ifneq ($(CROSSDEV),arm-elf-)
+  LDFLAGS		+= -nostartfiles -nodefaultlibs
+endif
+ifeq ($(CONFIG_DEBUG),y)
   LDFLAGS		+= -g
 endif
 
diff --git a/configs/eagle100/nettest/Make.defs b/configs/eagle100/nettest/Make.defs
index c858d506a3..420e639a1e 100644
--- a/configs/eagle100/nettest/Make.defs
+++ b/configs/eagle100/nettest/Make.defs
@@ -35,7 +35,13 @@
 
 include ${TOPDIR}/.config
 
-CROSSDEV		= arm-elf-
+# The default value for CROSSDEV can be overridden from the make command line:
+#   make                         -- Will build for the devkitARM toolchain
+#   make CROSSDEV=arm-eabi-      -- Will build for the devkitARM toolchain
+#   make CROSSDEV=arm-none-eabi- -- Will build for the CodeSourcery toolchain
+#   make CROSSDEV=arm-elf-       -- Will build for the NuttX buildroot toolchain
+
+CROSSDEV		= arm-eabi-
 CC			= $(CROSSDEV)gcc
 CXX			= $(CROSSDEV)g++
 CPP			= $(CROSSDEV)gcc -E
@@ -59,7 +65,12 @@ else
   ARCHOPTIMIZATION	= -Os -fno-strict-aliasing -fno-strength-reduce -fomit-frame-pointer
 endif
 
-ARCHCPUFLAGS		= -mtune=cortex-m3 -march=armv7-m -mfloat-abi=soft
+ifeq ($(CROSSDEV),arm-elf-)
+  ARCHCPUFLAGS		= -mtune=cortex-m3 -march=armv7-m -mfloat-abi=soft
+else
+  ARCHCPUFLAGS		= -mcpu=cortex-m3 -mthumb -mfloat-abi=soft
+endif
+
 ARCHDEFINES		=
 ARCHINCLUDES		= -I. -isystem $(TOPDIR)/include
 ARCHXXINCLUDES		= -I. -isystem $(TOPDIR)/include -isystem $(TOPDIR)/include/cxx
@@ -78,7 +89,10 @@ OBJEXT			= .o
 LIBEXT			= .a
 EXEEXT			=
 
-ifeq ("${CONFIG_DEBUG}","y")
+ifneq ($(CROSSDEV),arm-elf-)
+  LDFLAGS		+= -nostartfiles -nodefaultlibs
+endif
+ifeq ($(CONFIG_DEBUG),y)
   LDFLAGS		+= -g
 endif
 
diff --git a/configs/eagle100/nsh/Make.defs b/configs/eagle100/nsh/Make.defs
index df915ca594..385694db85 100644
--- a/configs/eagle100/nsh/Make.defs
+++ b/configs/eagle100/nsh/Make.defs
@@ -35,7 +35,13 @@
 
 include ${TOPDIR}/.config
 
-CROSSDEV		= arm-elf-
+# The default value for CROSSDEV can be overridden from the make command line:
+#   make                         -- Will build for the devkitARM toolchain
+#   make CROSSDEV=arm-eabi-      -- Will build for the devkitARM toolchain
+#   make CROSSDEV=arm-none-eabi- -- Will build for the CodeSourcery toolchain
+#   make CROSSDEV=arm-elf-       -- Will build for the NuttX buildroot toolchain
+
+CROSSDEV		= arm-eabi-
 CC			= $(CROSSDEV)gcc
 CXX			= $(CROSSDEV)g++
 CPP			= $(CROSSDEV)gcc -E
@@ -59,7 +65,12 @@ else
   ARCHOPTIMIZATION	= -Os -fno-strict-aliasing -fno-strength-reduce -fomit-frame-pointer
 endif
 
-ARCHCPUFLAGS		= -mtune=cortex-m3 -march=armv7-m -mfloat-abi=soft
+ifeq ($(CROSSDEV),arm-elf-)
+  ARCHCPUFLAGS		= -mtune=cortex-m3 -march=armv7-m -mfloat-abi=soft
+else
+  ARCHCPUFLAGS		= -mcpu=cortex-m3 -mthumb -mfloat-abi=soft
+endif
+
 ARCHDEFINES		=
 ARCHINCLUDES		= -I. -isystem $(TOPDIR)/include
 ARCHXXINCLUDES		= -I. -isystem $(TOPDIR)/include -isystem $(TOPDIR)/include/cxx
@@ -78,7 +89,10 @@ OBJEXT			= .o
 LIBEXT			= .a
 EXEEXT			=
 
-ifeq ("${CONFIG_DEBUG}","y")
+ifneq ($(CROSSDEV),arm-elf-)
+  LDFLAGS		+= -nostartfiles -nodefaultlibs
+endif
+ifeq ($(CONFIG_DEBUG),y)
   LDFLAGS		+= -g
 endif
 
diff --git a/configs/eagle100/ostest/Make.defs b/configs/eagle100/ostest/Make.defs
index dd785a7260..ee7ba87358 100644
--- a/configs/eagle100/ostest/Make.defs
+++ b/configs/eagle100/ostest/Make.defs
@@ -35,7 +35,13 @@
 
 include ${TOPDIR}/.config
 
-CROSSDEV		= arm-elf-
+# The default value for CROSSDEV can be overridden from the make command line:
+#   make                         -- Will build for the devkitARM toolchain
+#   make CROSSDEV=arm-eabi-      -- Will build for the devkitARM toolchain
+#   make CROSSDEV=arm-none-eabi- -- Will build for the CodeSourcery toolchain
+#   make CROSSDEV=arm-elf-       -- Will build for the NuttX buildroot toolchain
+
+CROSSDEV		= arm-eabi-
 CC			= $(CROSSDEV)gcc
 CXX			= $(CROSSDEV)g++
 CPP			= $(CROSSDEV)gcc -E
@@ -59,7 +65,12 @@ else
   ARCHOPTIMIZATION	= -Os -fno-strict-aliasing -fno-strength-reduce -fomit-frame-pointer
 endif
 
-ARCHCPUFLAGS		= -mtune=cortex-m3 -march=armv7-m -mfloat-abi=soft
+ifeq ($(CROSSDEV),arm-elf-)
+  ARCHCPUFLAGS		= -mtune=cortex-m3 -march=armv7-m -mfloat-abi=soft
+else
+  ARCHCPUFLAGS		= -mcpu=cortex-m3 -mthumb -mfloat-abi=soft
+endif
+
 ARCHDEFINES		=
 ARCHINCLUDES		= -I. -isystem $(TOPDIR)/include
 ARCHXXINCLUDES		= -I. -isystem $(TOPDIR)/include -isystem $(TOPDIR)/include/cxx
@@ -78,7 +89,10 @@ OBJEXT			= .o
 LIBEXT			= .a
 EXEEXT			=
 
-ifeq ("${CONFIG_DEBUG}","y")
+ifneq ($(CROSSDEV),arm-elf-)
+  LDFLAGS		+= -nostartfiles -nodefaultlibs
+endif
+ifeq ($(CONFIG_DEBUG),y)
   LDFLAGS		+= -g
 endif