-CFLAGS = -Wall -Os -fno-inline-functions -mlongcalls -DICACHE_FLASH -I.
-LDFLAGS = -nostdlib -Wl,--no-check-sections -u call_user_start -Wl,-static
+CFLAGS = -Wall -Os -fno-inline-functions -mlongcalls -DICACHE_FLASH -I. \
+ -I$(SDKDIR)/xtensa-lx106-elf/include
+LDFLAGS = -nostdlib -Wl,--no-check-sections -Wl,--gc-sections -Wl,-static \
+ -u call_user_start \
+ -L$(SDKDIR)/xtensa-lx106-elf/lib