The toolchain isn't built with -mcallee-super-interworking enabled. Could we get that turned on? It is needed to make calls to thumb code in ROM.
arm-linux-gnueabi-gcc -g -DDEBUG -Os -fno-strict-aliasing -fno-common -ffixed-r8 -ffunction-sections -msoft-float -Wcast-align -Wall -D__KERNEL__ -DTEXT_BASE= -fno-builtin -ffreestanding -isystem /usr/lib/gcc/arm-linux-gnueabi/4.5.1/include -pipe -march=armv4t -mlong-calls -mtune=arm7tdmi-s -DCONFIG_ARM -D__ARM__ -mthumb-interwork -Wall -Wstrict-prototypes -Wcast-align -Wextra -Werror -Iobj_redbee-econotag_board -I../board -DBOARD=redbee-econotag -I../lib/include -I../src -I. -mthumb -mcallee-super-interworking -MMD -c -o obj_redbee-econotag_board/sleep.o sleep.c sleep.c:1:0: error: AAPCS does not support -mcallee-super-interworking