Build error for Amd64

Hi, I'm a newbie for L4ka:pistachio, I build the __LASTEST__ pistachio
kernel on  my amd64 5000+ debain lenny box,  with following basic
configuration:
---------------------------------------------------------------------------------------------------------------------------
ARCH=x86
SUBARCH=x64
CPU=k8
PLATFORM=pc99
...
-----------------------------------------------------------------------------------------------------------------------------

but when I enable CONFIG_SMP_IDLE_POLL
----------------------------------------------------------------------------------------------------------------------------
#define CONFIG_SMP 1
#define CONFIG_SMP_MAX_PROCS 4
#define CONFIG_SMP_IDLE_POLL               // enable IDLE_POLL
----------------------------------------------------------------------------------------------------------------------------

build failed with errors:

/home/ambrosehua/project/l4_kernel/l4ka/l4ka-pistachio/kernel/src/api/v4/schedul
                                                     e.cc:531:
undefined reference to `processor_sleep()'
kdb/platform/pc99/io.o: In function `getc_serial':
/home/ambrosehua/project/l4_kernel/l4ka/l4ka-pistachio/kernel/kdb/platform/pc99/
                                                     io.cc:344:
undefined reference to `processor_sleep()'
make[1]: *** [x86-kernel] Error 1
make[1]: Leaving directory `/home/ambrosehua/project/l4_kernel/l4ka/build-amd64'
make: *** [all] Error 2

otherwise, with CONFIG_SMP_IDLE_POLL disabled, build succeeded.

I search the code repo, and  found no implementation for function
processor_sleep in schedule.h.
and I also search the mail archive found no related info. Is this
feature unavailable or did I miss something ?