Errors compiling 2.6.7-mm2

[limaunion]

Hello!

While trying to compile 2.6.7-mm1 or -mm2 under FC2 I got the following 
errors:


   CC      init/version.o
   LD      init/built-in.o
   LD      .tmp_vmlinux1
arch/i386/kernel/built-in.o(.text+0xbe14): In function `powernow_acpi_init':
: undefined reference to `acpi_processor_register_performance'
arch/i386/kernel/built-in.o(.text+0xbe3b): In function `powernow_acpi_init':
: undefined reference to `acpi_processor_unregister_performance'
arch/i386/kernel/built-in.o(.exit.text+0x3b): In function `powernow_exit':
: undefined reference to `acpi_processor_unregister_performance'
make: *** [.tmp_vmlinux1] Error 1

Does anyone have an idea of what's going on ?, I often upgrade my 
kernels but don't know how to solve this. Should I post a mail in the LKML ?

Thanks for any suggestion.
LU