--- arch/ia64/include/asm/system.h

+++ arch/ia64/include/asm/system.h

@@ -281,10 +281,6 @@ void cpu_idle_wait(void);

void default_idle(void);

-#ifdef CONFIG_VIRT_CPU_ACCOUNTING

-extern void account_system_vtime(struct task_struct *);

-#endif

-

#endif /* __KERNEL__ */

#endif /* __ASSEMBLY__ */