CPPPATH should be string.

bsp/jz47xx/SConscript

@@ -6,7 +6,7 @@ src_bsp   = ['application.c', 'startup.c', 'board.c']
 src_drv   = ['uart.c']
 
 src	= File(src_bsp + src_drv)
-CPPPATH = Dir('#')
+CPPPATH = str(Dir('#'))
 group = DefineGroup('Startup', src, depend = [''], CPPPATH = CPPPATH)
 
 Return('group')

bsp/taihu/applications/SConscript

@@ -4,7 +4,7 @@ from building import *
 
 cwd = GetCurrentDir()
 src = Glob('*.c')
-CPPPATH = [cwd, Dir('#')]
+CPPPATH = [cwd, str(Dir('#'))]
 
 group = DefineGroup('Applications', src, depend = [''], CPPPATH = CPPPATH)