diff --git a/configs/eagle100/README.txt b/configs/eagle100/README.txt
index 36be8635905..c0219a25a40 100644
--- a/configs/eagle100/README.txt
+++ b/configs/eagle100/README.txt
@@ -38,6 +38,27 @@ GNU Toolchain Options
   Of course, hard coding this CROSS_COMPILE value in Make.defs file will save
   some repetitive typing.
 
+  NOTE: the CodeSourcery and devkitARM toolchains are Windows native toolchains.
+  The NuttX buildroot toolchain is a Cygwin toolchain.  There are several limitations
+  to using a Windows based toolchain in a Cygwin environment.  The two biggestg are:
+
+  1. The Windows toolchain cannot follow Cygwin paths.  Path conversions are
+     performed automatically in the Cygwin makefiles using the 'cygpath' utility
+     but you might easily find some new path problems.  If so, check out 'cygpath -w'
+
+  2. Windows toolchains cannot follow Cygwin symbolic links.  Many symbolic links
+     are used in Nuttx (e.g., include/arch).  The make system works around these
+     problems for the Windows tools by copying directories instead of linking them.
+     But this can also cause some confusion for you:  For example, you may edit
+     a file in a "linked" directory and find that your changes had not effect.
+     That is because you are building the copy of the file in the "fake" symbolic
+     directory.  If you use a Windows toolchain, you should get in the habit of
+     making like this:
+       
+       make clean_context; make CROSSDEV=arm-none-eabi-
+
+     An alias in your .bashrc file might make that less painful.
+ 
 NuttX buildroot Toolchain
 ^^^^^^^^^^^^^^^^^^^^^^^^^
 
diff --git a/configs/eagle100/httpd/Make.defs b/configs/eagle100/httpd/Make.defs
index cf8e2e98dfa..cc0cba87a3c 100644
--- a/configs/eagle100/httpd/Make.defs
+++ b/configs/eagle100/httpd/Make.defs
@@ -66,17 +66,24 @@ else
 endif
 
 ifeq ($(CROSSDEV),arm-elf-)
+  MKDEP			= $(TOPDIR)/tools/mkdeps.sh
   ARCHCPUFLAGS		= -mtune=cortex-m3 -march=armv7-m -mfloat-abi=soft
+  ARCHINCLUDES		= -I. -isystem $(TOPDIR)/include
+  ARCHXXINCLUDES	= -I. -isystem $(TOPDIR)/include -isystem $(TOPDIR)/include/cxx
+  ARCHSCRIPT		= -T$(TOPDIR)/configs/$(CONFIG_ARCH_BOARD)/httpd/ld.script
 else
+  WINTOOL		= y
+  DIRLINK 		= $(TOPDIR)/tools/winlink.sh
+  DIRUNLINK		= $(TOPDIR)/tools/unlink.sh
+  MKDEP			= $(TOPDIR)/tools/mknulldeps.sh
   ARCHCPUFLAGS		= -mcpu=cortex-m3 -mthumb -mfloat-abi=soft
+  ARCHINCLUDES		= -I. -isystem "${shell cygpath -w $(TOPDIR)/include}"
+  ARCHXXINCLUDES	= -I. -isystem "${shell cygpath -w $(TOPDIR)/include}" -isystem "${shell cygpath -w $(TOPDIR)/include/cxx}"
+  ARCHSCRIPT		= -T "${shell cygpath -w $(TOPDIR)/configs/$(CONFIG_ARCH_BOARD)/httpd/ld.script}"
 endif
 
 ARCHDEFINES		=
-ARCHINCLUDES		= -I. -isystem $(TOPDIR)/include
-ARCHXXINCLUDES		= -I. -isystem $(TOPDIR)/include -isystem $(TOPDIR)/include/cxx
-
 ARCHPICFLAGS		= -fpic
-ARCHSCRIPT		= -T$(TOPDIR)/configs/$(CONFIG_ARCH_BOARD)/httpd/ld.script
 
 CFLAGS			= $(ARCHCFLAGS) $(ARCHWARNINGS) $(ARCHOPTIMIZATION) \
 			  $(ARCHCPUFLAGS) $(ARCHINCLUDES) $(ARCHDEFINES) -pipe
@@ -125,8 +132,6 @@ define CLEAN
 	@rm -f *.o *.a
 endef
 
-MKDEP			= $(TOPDIR)/tools/mkdeps.sh
-
 HOSTCC			= gcc
 HOSTINCLUDES		= -I.
 HOSTCFLAGS		= -Wall -Wstrict-prototypes -Wshadow -g -pipe
diff --git a/configs/eagle100/nettest/Make.defs b/configs/eagle100/nettest/Make.defs
index 420e639a1ef..acca26e5762 100644
--- a/configs/eagle100/nettest/Make.defs
+++ b/configs/eagle100/nettest/Make.defs
@@ -66,17 +66,24 @@ else
 endif
 
 ifeq ($(CROSSDEV),arm-elf-)
+  MKDEP			= $(TOPDIR)/tools/mkdeps.sh
   ARCHCPUFLAGS		= -mtune=cortex-m3 -march=armv7-m -mfloat-abi=soft
+  ARCHINCLUDES		= -I. -isystem $(TOPDIR)/include
+  ARCHXXINCLUDES	= -I. -isystem $(TOPDIR)/include -isystem $(TOPDIR)/include/cxx
+  ARCHSCRIPT		= -T$(TOPDIR)/configs/$(CONFIG_ARCH_BOARD)/nettest/ld.script
 else
+  WINTOOL		= y
+  DIRLINK 		= $(TOPDIR)/tools/winlink.sh
+  DIRUNLINK		= $(TOPDIR)/tools/unlink.sh
+  MKDEP			= $(TOPDIR)/tools/mknulldeps.sh
   ARCHCPUFLAGS		= -mcpu=cortex-m3 -mthumb -mfloat-abi=soft
+  ARCHINCLUDES		= -I. -isystem "${shell cygpath -w $(TOPDIR)/include}"
+  ARCHXXINCLUDES	= -I. -isystem "${shell cygpath -w $(TOPDIR)/include}" -isystem "${shell cygpath -w $(TOPDIR)/include/cxx}"
+  ARCHSCRIPT		= -T "${shell cygpath -w $(TOPDIR)/configs/$(CONFIG_ARCH_BOARD)/nettest/ld.script}"
 endif
 
 ARCHDEFINES		=
-ARCHINCLUDES		= -I. -isystem $(TOPDIR)/include
-ARCHXXINCLUDES		= -I. -isystem $(TOPDIR)/include -isystem $(TOPDIR)/include/cxx
-
 ARCHPICFLAGS		= -fpic
-ARCHSCRIPT		= -T$(TOPDIR)/configs/$(CONFIG_ARCH_BOARD)/nettest/ld.script
 
 CFLAGS			= $(ARCHCFLAGS) $(ARCHWARNINGS) $(ARCHOPTIMIZATION) \
 			  $(ARCHCPUFLAGS) $(ARCHINCLUDES) $(ARCHDEFINES) -pipe
@@ -125,8 +132,6 @@ define CLEAN
 	@rm -f *.o *.a
 endef
 
-MKDEP			= $(TOPDIR)/tools/mkdeps.sh
-
 HOSTCC			= gcc
 HOSTINCLUDES		= -I.
 HOSTCFLAGS		= -Wall -Wstrict-prototypes -Wshadow -g -pipe
diff --git a/configs/eagle100/nsh/Make.defs b/configs/eagle100/nsh/Make.defs
index 385694db853..9527be6e408 100644
--- a/configs/eagle100/nsh/Make.defs
+++ b/configs/eagle100/nsh/Make.defs
@@ -66,17 +66,24 @@ else
 endif
 
 ifeq ($(CROSSDEV),arm-elf-)
+  MKDEP			= $(TOPDIR)/tools/mkdeps.sh
   ARCHCPUFLAGS		= -mtune=cortex-m3 -march=armv7-m -mfloat-abi=soft
+  ARCHINCLUDES		= -I. -isystem $(TOPDIR)/include
+  ARCHXXINCLUDES	= -I. -isystem $(TOPDIR)/include -isystem $(TOPDIR)/include/cxx
+  ARCHSCRIPT		= -T$(TOPDIR)/configs/$(CONFIG_ARCH_BOARD)/nsh/ld.script
 else
+  WINTOOL		= y
+  DIRLINK 		= $(TOPDIR)/tools/winlink.sh
+  DIRUNLINK		= $(TOPDIR)/tools/unlink.sh
+  MKDEP			= $(TOPDIR)/tools/mknulldeps.sh
   ARCHCPUFLAGS		= -mcpu=cortex-m3 -mthumb -mfloat-abi=soft
+  ARCHINCLUDES		= -I. -isystem "${shell cygpath -w $(TOPDIR)/include}"
+  ARCHXXINCLUDES	= -I. -isystem "${shell cygpath -w $(TOPDIR)/include}" -isystem "${shell cygpath -w $(TOPDIR)/include/cxx}"
+  ARCHSCRIPT		= -T "${shell cygpath -w $(TOPDIR)/configs/$(CONFIG_ARCH_BOARD)/nsh/ld.script}"
 endif
 
 ARCHDEFINES		=
-ARCHINCLUDES		= -I. -isystem $(TOPDIR)/include
-ARCHXXINCLUDES		= -I. -isystem $(TOPDIR)/include -isystem $(TOPDIR)/include/cxx
-
 ARCHPICFLAGS		= -fpic
-ARCHSCRIPT		= -T$(TOPDIR)/configs/$(CONFIG_ARCH_BOARD)/nsh/ld.script
 
 CFLAGS			= $(ARCHCFLAGS) $(ARCHWARNINGS) $(ARCHOPTIMIZATION) \
 			  $(ARCHCPUFLAGS) $(ARCHINCLUDES) $(ARCHDEFINES) -pipe
@@ -125,8 +132,6 @@ define CLEAN
 	@rm -f *.o *.a
 endef
 
-MKDEP			= $(TOPDIR)/tools/mkdeps.sh
-
 HOSTCC			= gcc
 HOSTINCLUDES		= -I.
 HOSTCFLAGS		= -Wall -Wstrict-prototypes -Wshadow -g -pipe
diff --git a/configs/eagle100/ostest/Make.defs b/configs/eagle100/ostest/Make.defs
index ee7ba873583..10c344e25a7 100644
--- a/configs/eagle100/ostest/Make.defs
+++ b/configs/eagle100/ostest/Make.defs
@@ -66,17 +66,24 @@ else
 endif
 
 ifeq ($(CROSSDEV),arm-elf-)
+  MKDEP			= $(TOPDIR)/tools/mkdeps.sh
   ARCHCPUFLAGS		= -mtune=cortex-m3 -march=armv7-m -mfloat-abi=soft
+  ARCHINCLUDES		= -I. -isystem $(TOPDIR)/include
+  ARCHXXINCLUDES	= -I. -isystem $(TOPDIR)/include -isystem $(TOPDIR)/include/cxx
+  ARCHSCRIPT		= -T$(TOPDIR)/configs/$(CONFIG_ARCH_BOARD)/ostest/ld.script
 else
+  WINTOOL		= y
+  DIRLINK 		= $(TOPDIR)/tools/winlink.sh
+  DIRUNLINK		= $(TOPDIR)/tools/unlink.sh
+  MKDEP			= $(TOPDIR)/tools/mknulldeps.sh
   ARCHCPUFLAGS		= -mcpu=cortex-m3 -mthumb -mfloat-abi=soft
+  ARCHINCLUDES		= -I. -isystem "${shell cygpath -w $(TOPDIR)/include}"
+  ARCHXXINCLUDES	= -I. -isystem "${shell cygpath -w $(TOPDIR)/include}" -isystem "${shell cygpath -w $(TOPDIR)/include/cxx}"
+  ARCHSCRIPT		= -T "${shell cygpath -w $(TOPDIR)/configs/$(CONFIG_ARCH_BOARD)/ostest/ld.script}"
 endif
 
 ARCHDEFINES		=
-ARCHINCLUDES		= -I. -isystem $(TOPDIR)/include
-ARCHXXINCLUDES		= -I. -isystem $(TOPDIR)/include -isystem $(TOPDIR)/include/cxx
-
 ARCHPICFLAGS		= -fpic
-ARCHSCRIPT		= -T$(TOPDIR)/configs/$(CONFIG_ARCH_BOARD)/ostest/ld.script
 
 CFLAGS			= $(ARCHCFLAGS) $(ARCHWARNINGS) $(ARCHOPTIMIZATION) \
 			  $(ARCHCPUFLAGS) $(ARCHINCLUDES) $(ARCHDEFINES) -pipe
@@ -125,8 +132,6 @@ define CLEAN
 	@rm -f *.o *.a
 endef
 
-MKDEP			= $(TOPDIR)/tools/mkdeps.sh
-
 HOSTCC			= gcc
 HOSTINCLUDES		= -I.
 HOSTCFLAGS		= -Wall -Wstrict-prototypes -Wshadow -g -pipe
diff --git a/configs/eagle100/src/Makefile b/configs/eagle100/src/Makefile
index f2ca3a0d6ed..79fb8a558dc 100644
--- a/configs/eagle100/src/Makefile
+++ b/configs/eagle100/src/Makefile
@@ -49,7 +49,13 @@ SRCS		= $(ASRCS) $(CSRCS)
 OBJS		= $(AOBJS) $(COBJS)
 
 ARCH_SRCDIR	= $(TOPDIR)/arch/$(CONFIG_ARCH)/src
-CFLAGS		+= -I$(ARCH_SRCDIR)/chip -I$(ARCH_SRCDIR)/common -I$(ARCH_SRCDIR)/cortexm3
+ifeq ($(WINTOOL),y)
+  CFLAGS	+= -I "${shell cygpath -w $(ARCH_SRCDIR)/chip}" \
+  		   -I "${shell cygpath -w $(ARCH_SRCDIR)/common}" \
+  		   -I "${shell cygpath -w $(ARCH_SRCDIR)/cortexm3}"
+else
+  CFLAGS	+= -I$(ARCH_SRCDIR)/chip -I$(ARCH_SRCDIR)/common -I$(ARCH_SRCDIR)/cortexm3
+endif
 
 all: libboard$(LIBEXT)