arch/parisc/kernel/smp.c - maze/linux - Git at Google

 /*
 ** SMP Support
 **
 ** Copyright (C) 1999 Walt Drummond <drummond@valinux.com>
 ** Copyright (C) 1999 David Mosberger-Tang <davidm@hpl.hp.com>
 ** Copyright (C) 2001,2004 Grant Grundler <grundler@parisc-linux.org>
 **
 ** Lots of stuff stolen from arch/alpha/kernel/smp.c
 ** ...and then parisc stole from arch/ia64/kernel/smp.c. Thanks David! :^)
 **
 ** Thanks to John Curry and Ullas Ponnadi. I learned a lot from their work.
 ** -grant (1/12/2001)
 **
 **	This program is free software; you can redistribute it and/or modify
 **	it under the terms of the GNU General Public License as published by
 **      the Free Software Foundation; either version 2 of the License, or
 **      (at your option) any later version.
 */
 #include <linux/types.h>
 #include <linux/spinlock.h>

 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/sched.h>
 #include <linux/init.h>
 #include <linux/interrupt.h>
 #include <linux/smp.h>
 #include <linux/kernel_stat.h>
 #include <linux/mm.h>
 #include <linux/err.h>
 #include <linux/delay.h>
 #include <linux/bitops.h>
 #include <linux/ftrace.h>
 #include <linux/cpu.h>

 #include <linux/atomic.h>
 #include <asm/current.h>
 #include <asm/delay.h>
 #include <asm/tlbflush.h>

 #include <asm/io.h>
 #include <asm/irq.h>		/* for CPU_IRQ_REGION and friends */
 #include <asm/mmu_context.h>
 #include <asm/page.h>
 #include <asm/pgtable.h>
 #include <asm/pgalloc.h>
 #include <asm/processor.h>
 #include <asm/ptrace.h>
 #include <asm/unistd.h>
 #include <asm/cacheflush.h>

 #undef DEBUG_SMP
 #ifdef DEBUG_SMP
 static int smp_debug_lvl = 0;
 #define smp_debug(lvl, printargs...)		\
 		if (lvl >= smp_debug_lvl)	\
 			printk(printargs);
 #else
 #define smp_debug(lvl, ...)	do { } while(0)
 #endif /* DEBUG_SMP */

 volatile struct task_struct *smp_init_current_idle_task;

 /* track which CPU is booting */
 static volatile int cpu_now_booting __cpuinitdata;

 static int parisc_max_cpus __cpuinitdata = 1;

 static DEFINE_PER_CPU(spinlock_t, ipi_lock);

 enum ipi_message_type {
 	IPI_NOP=0,
 	IPI_RESCHEDULE=1,
 	IPI_CALL_FUNC,
 	IPI_CALL_FUNC_SINGLE,
 	IPI_CPU_START,
 	IPI_CPU_STOP,
 	IPI_CPU_TEST
 };


 /********** SMP inter processor interrupt and communication routines */

 #undef PER_CPU_IRQ_REGION
 #ifdef PER_CPU_IRQ_REGION
 /* XXX REVISIT Ignore for now.
 **    *May* need this "hook" to register IPI handler
 **    once we have perCPU ExtIntr switch tables.
 */
 static void
 ipi_init(int cpuid)
 {
 #error verify IRQ_OFFSET(IPI_IRQ) is ipi_interrupt() in new IRQ region

 	if(cpu_online(cpuid) )
 	{
 		switch_to_idle_task(current);
 	}

 	return;
 }
 #endif


 /*
 ** Yoink this CPU from the runnable list...
 **
 */
 static void
 halt_processor(void)
 {
 	/* REVISIT : redirect I/O Interrupts to another CPU? */
 	/* REVISIT : does PM *know* this CPU isn't available? */
 	set_cpu_online(smp_processor_id(), false);
 	local_irq_disable();
 	for (;;)
 		;
 }


 irqreturn_t __irq_entry
 ipi_interrupt(int irq, void *dev_id)
 {
 	int this_cpu = smp_processor_id();
 	struct cpuinfo_parisc *p = &per_cpu(cpu_data, this_cpu);
 	unsigned long ops;
 	unsigned long flags;

 	/* Count this now; we may make a call that never returns. */
 	inc_irq_stat(irq_call_count);

 	mb();	/* Order interrupt and bit testing. */

 	for (;;) {
 		spinlock_t *lock = &per_cpu(ipi_lock, this_cpu);
 		spin_lock_irqsave(lock, flags);
 		ops = p->pending_ipi;
 		p->pending_ipi = 0;
 		spin_unlock_irqrestore(lock, flags);

 		mb(); /* Order bit clearing and data access. */

 		if (!ops)
 		    break;

 		while (ops) {
 			unsigned long which = ffz(~ops);

 			ops &= ~(1 << which);

 			switch (which) {
 			case IPI_NOP:
 				smp_debug(100, KERN_DEBUG "CPU%d IPI_NOP\n", this_cpu);
 				break;

 			case IPI_RESCHEDULE:
 				smp_debug(100, KERN_DEBUG "CPU%d IPI_RESCHEDULE\n", this_cpu);
 				inc_irq_stat(irq_resched_count);
 				scheduler_ipi();
 				break;

 			case IPI_CALL_FUNC:
 				smp_debug(100, KERN_DEBUG "CPU%d IPI_CALL_FUNC\n", this_cpu);
 				generic_smp_call_function_interrupt();
 				break;

 			case IPI_CALL_FUNC_SINGLE:
 				smp_debug(100, KERN_DEBUG "CPU%d IPI_CALL_FUNC_SINGLE\n", this_cpu);
 				generic_smp_call_function_single_interrupt();
 				break;

 			case IPI_CPU_START:
 				smp_debug(100, KERN_DEBUG "CPU%d IPI_CPU_START\n", this_cpu);
 				break;

 			case IPI_CPU_STOP:
 				smp_debug(100, KERN_DEBUG "CPU%d IPI_CPU_STOP\n", this_cpu);
 				halt_processor();
 				break;

 			case IPI_CPU_TEST:
 				smp_debug(100, KERN_DEBUG "CPU%d is alive!\n", this_cpu);
 				break;

 			default:
 				printk(KERN_CRIT "Unknown IPI num on CPU%d: %lu\n",
 					this_cpu, which);
 				return IRQ_NONE;
 			} /* Switch */
 		/* let in any pending interrupts */
 		local_irq_enable();
 		local_irq_disable();
 		} /* while (ops) */
 	}
 	return IRQ_HANDLED;
 }


 static inline void
 ipi_send(int cpu, enum ipi_message_type op)
 {
 	struct cpuinfo_parisc *p = &per_cpu(cpu_data, cpu);
 	spinlock_t *lock = &per_cpu(ipi_lock, cpu);
 	unsigned long flags;

 	spin_lock_irqsave(lock, flags);
 	p->pending_ipi |= 1 << op;
 	gsc_writel(IPI_IRQ - CPU_IRQ_BASE, p->hpa);
 	spin_unlock_irqrestore(lock, flags);
 }

 static void
 send_IPI_mask(const struct cpumask *mask, enum ipi_message_type op)
 {
 	int cpu;

 	for_each_cpu(cpu, mask)
 		ipi_send(cpu, op);
 }

 static inline void
 send_IPI_single(int dest_cpu, enum ipi_message_type op)
 {
 	BUG_ON(dest_cpu == NO_PROC_ID);

 	ipi_send(dest_cpu, op);
 }

 static inline void
 send_IPI_allbutself(enum ipi_message_type op)
 {
 	int i;

 	for_each_online_cpu(i) {
 		if (i != smp_processor_id())
 			send_IPI_single(i, op);
 	}
 }


 inline void
 smp_send_stop(void)	{ send_IPI_allbutself(IPI_CPU_STOP); }

 static inline void
 smp_send_start(void)	{ send_IPI_allbutself(IPI_CPU_START); }

 void
 smp_send_reschedule(int cpu) { send_IPI_single(cpu, IPI_RESCHEDULE); }

 void
 smp_send_all_nop(void)
 {
 	send_IPI_allbutself(IPI_NOP);
 }

 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
 {
 	send_IPI_mask(mask, IPI_CALL_FUNC);
 }

 void arch_send_call_function_single_ipi(int cpu)
 {
 	send_IPI_single(cpu, IPI_CALL_FUNC_SINGLE);
 }

 /*
  * Called by secondaries to update state and initialize CPU registers.
  */
 static void __init
 smp_cpu_init(int cpunum)
 {
 	extern int init_per_cpu(int);  /* arch/parisc/kernel/processor.c */
 	extern void init_IRQ(void);    /* arch/parisc/kernel/irq.c */
 	extern void start_cpu_itimer(void); /* arch/parisc/kernel/time.c */

 	/* Set modes and Enable floating point coprocessor */
 	(void) init_per_cpu(cpunum);

 	disable_sr_hashing();

 	mb();

 	/* Well, support 2.4 linux scheme as well. */
 	if (cpu_online(cpunum))	{
 		extern void machine_halt(void); /* arch/parisc.../process.c */

 		printk(KERN_CRIT "CPU#%d already initialized!\n", cpunum);
 		machine_halt();
 	}

 	notify_cpu_starting(cpunum);

 	set_cpu_online(cpunum, true);

 	/* Initialise the idle task for this CPU */
 	atomic_inc(&init_mm.mm_count);
 	current->active_mm = &init_mm;
 	BUG_ON(current->mm);
 	enter_lazy_tlb(&init_mm, current);

 	init_IRQ();   /* make sure no IRQs are enabled or pending */
 	start_cpu_itimer();
 }


 /*
  * Slaves start using C here. Indirectly called from smp_slave_stext.
  * Do what start_kernel() and main() do for boot strap processor (aka monarch)
  */
 void __init smp_callin(void)
 {
 	int slave_id = cpu_now_booting;

 	smp_cpu_init(slave_id);
 	preempt_disable();

 	flush_cache_all_local(); /* start with known state */
 	flush_tlb_all_local(NULL);

 	local_irq_enable();  /* Interrupts have been off until now */

 	cpu_startup_entry(CPUHP_ONLINE);

 	/* NOTREACHED */
 	panic("smp_callin() AAAAaaaaahhhh....\n");
 }

 /*
  * Bring one cpu online.
  */
 int __cpuinit smp_boot_one_cpu(int cpuid, struct task_struct *idle)
 {
 	const struct cpuinfo_parisc *p = &per_cpu(cpu_data, cpuid);
 	long timeout;

 	task_thread_info(idle)->cpu = cpuid;

 	/* Let _start know what logical CPU we're booting
 	** (offset into init_tasks[],cpu_data[])
 	*/
 	cpu_now_booting = cpuid;

 	/*
 	** boot strap code needs to know the task address since
 	** it also contains the process stack.
 	*/
 	smp_init_current_idle_task = idle ;
 	mb();

 	printk(KERN_INFO "Releasing cpu %d now, hpa=%lx\n", cpuid, p->hpa);

 	/*
 	** This gets PDC to release the CPU from a very tight loop.
 	**
 	** From the PA-RISC 2.0 Firmware Architecture Reference Specification:
 	** "The MEM_RENDEZ vector specifies the location of OS_RENDEZ which
 	** is executed after receiving the rendezvous signal (an interrupt to
 	** EIR{0}). MEM_RENDEZ is valid only when it is nonzero and the
 	** contents of memory are valid."
 	*/
 	gsc_writel(TIMER_IRQ - CPU_IRQ_BASE, p->hpa);
 	mb();

 	/*
 	 * OK, wait a bit for that CPU to finish staggering about.
 	 * Slave will set a bit when it reaches smp_cpu_init().
 	 * Once the "monarch CPU" sees the bit change, it can move on.
 	 */
 	for (timeout = 0; timeout < 10000; timeout++) {
 		if(cpu_online(cpuid)) {
 			/* Which implies Slave has started up */
 			cpu_now_booting = 0;
 			smp_init_current_idle_task = NULL;
 			goto alive ;
 		}
 		udelay(100);
 		barrier();
 	}
 	printk(KERN_CRIT "SMP: CPU:%d is stuck.\n", cpuid);
 	return -1;

 alive:
 	/* Remember the Slave data */
 	smp_debug(100, KERN_DEBUG "SMP: CPU:%d came alive after %ld _us\n",
 		cpuid, timeout * 100);
 	return 0;
 }

 void __init smp_prepare_boot_cpu(void)
 {
 	int bootstrap_processor = per_cpu(cpu_data, 0).cpuid;

 	/* Setup BSP mappings */
 	printk(KERN_INFO "SMP: bootstrap CPU ID is %d\n", bootstrap_processor);

 	set_cpu_online(bootstrap_processor, true);
 	set_cpu_present(bootstrap_processor, true);
 }


 /*
 ** inventory.c:do_inventory() hasn't yet been run and thus we
 ** don't 'discover' the additional CPUs until later.
 */
 void __init smp_prepare_cpus(unsigned int max_cpus)
 {
 	int cpu;

 	for_each_possible_cpu(cpu)
 		spin_lock_init(&per_cpu(ipi_lock, cpu));

 	init_cpu_present(cpumask_of(0));

 	parisc_max_cpus = max_cpus;
 	if (!max_cpus)
 		printk(KERN_INFO "SMP mode deactivated.\n");
 }


 void smp_cpus_done(unsigned int cpu_max)
 {
 	return;
 }


 int __cpuinit __cpu_up(unsigned int cpu, struct task_struct *tidle)
 {
 	if (cpu != 0 && cpu < parisc_max_cpus)
 		smp_boot_one_cpu(cpu, tidle);

 	return cpu_online(cpu) ? 0 : -ENOSYS;
 }

 #ifdef CONFIG_PROC_FS
 int __init
 setup_profiling_timer(unsigned int multiplier)
 {
 	return -EINVAL;
 }
 #endif
	/*
	** SMP Support
	**
	** Copyright (C) 1999 Walt Drummond <drummond@valinux.com>
	** Copyright (C) 1999 David Mosberger-Tang <davidm@hpl.hp.com>
	** Copyright (C) 2001,2004 Grant Grundler <grundler@parisc-linux.org>
	**
	** Lots of stuff stolen from arch/alpha/kernel/smp.c
	** ...and then parisc stole from arch/ia64/kernel/smp.c. Thanks David! :^)
	**
	** Thanks to John Curry and Ullas Ponnadi. I learned a lot from their work.
	** -grant (1/12/2001)
	**
	** This program is free software; you can redistribute it and/or modify
	** it under the terms of the GNU General Public License as published by
	** the Free Software Foundation; either version 2 of the License, or
	** (at your option) any later version.
	*/
	#include <linux/types.h>
	#include <linux/spinlock.h>

	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/sched.h>
	#include <linux/init.h>
	#include <linux/interrupt.h>
	#include <linux/smp.h>
	#include <linux/kernel_stat.h>
	#include <linux/mm.h>
	#include <linux/err.h>
	#include <linux/delay.h>
	#include <linux/bitops.h>
	#include <linux/ftrace.h>
	#include <linux/cpu.h>

	#include <linux/atomic.h>
	#include <asm/current.h>
	#include <asm/delay.h>
	#include <asm/tlbflush.h>

	#include <asm/io.h>
	#include <asm/irq.h> /* for CPU_IRQ_REGION and friends */
	#include <asm/mmu_context.h>
	#include <asm/page.h>
	#include <asm/pgtable.h>
	#include <asm/pgalloc.h>
	#include <asm/processor.h>
	#include <asm/ptrace.h>
	#include <asm/unistd.h>
	#include <asm/cacheflush.h>

	#undef DEBUG_SMP
	#ifdef DEBUG_SMP
	static int smp_debug_lvl = 0;
	#define smp_debug(lvl, printargs...) \
	if (lvl >= smp_debug_lvl) \
	printk(printargs);
	#else
	#define smp_debug(lvl, ...) do { } while(0)
	#endif /* DEBUG_SMP */

	volatile struct task_struct *smp_init_current_idle_task;

	/* track which CPU is booting */
	static volatile int cpu_now_booting __cpuinitdata;

	static int parisc_max_cpus __cpuinitdata = 1;

	static DEFINE_PER_CPU(spinlock_t, ipi_lock);

	enum ipi_message_type {
	IPI_NOP=0,
	IPI_RESCHEDULE=1,
	IPI_CALL_FUNC,
	IPI_CALL_FUNC_SINGLE,
	IPI_CPU_START,
	IPI_CPU_STOP,
	IPI_CPU_TEST
	};


	/********** SMP inter processor interrupt and communication routines */

	#undef PER_CPU_IRQ_REGION
	#ifdef PER_CPU_IRQ_REGION
	/* XXX REVISIT Ignore for now.
	** May need this "hook" to register IPI handler
	** once we have perCPU ExtIntr switch tables.
	*/
	static void
	ipi_init(int cpuid)
	{
	#error verify IRQ_OFFSET(IPI_IRQ) is ipi_interrupt() in new IRQ region

	if(cpu_online(cpuid) )
	{
	switch_to_idle_task(current);
	}

	return;
	}
	#endif


	/*
	** Yoink this CPU from the runnable list...
	**
	*/
	static void
	halt_processor(void)
	{
	/* REVISIT : redirect I/O Interrupts to another CPU? */
	/* REVISIT : does PM know this CPU isn't available? */
	set_cpu_online(smp_processor_id(), false);
	local_irq_disable();
	for (;;)
	;
	}


	irqreturn_t __irq_entry
	ipi_interrupt(int irq, void *dev_id)
	{
	int this_cpu = smp_processor_id();
	struct cpuinfo_parisc *p = &per_cpu(cpu_data, this_cpu);
	unsigned long ops;
	unsigned long flags;

	/* Count this now; we may make a call that never returns. */
	inc_irq_stat(irq_call_count);

	mb(); /* Order interrupt and bit testing. */

	for (;;) {
	spinlock_t *lock = &per_cpu(ipi_lock, this_cpu);
	spin_lock_irqsave(lock, flags);
	ops = p->pending_ipi;
	p->pending_ipi = 0;
	spin_unlock_irqrestore(lock, flags);

	mb(); /* Order bit clearing and data access. */

	if (!ops)
	break;

	while (ops) {
	unsigned long which = ffz(~ops);

	ops &= ~(1 << which);

	switch (which) {
	case IPI_NOP:
	smp_debug(100, KERN_DEBUG "CPU%d IPI_NOP\n", this_cpu);
	break;

	case IPI_RESCHEDULE:
	smp_debug(100, KERN_DEBUG "CPU%d IPI_RESCHEDULE\n", this_cpu);
	inc_irq_stat(irq_resched_count);
	scheduler_ipi();
	break;

	case IPI_CALL_FUNC:
	smp_debug(100, KERN_DEBUG "CPU%d IPI_CALL_FUNC\n", this_cpu);
	generic_smp_call_function_interrupt();
	break;

	case IPI_CALL_FUNC_SINGLE:
	smp_debug(100, KERN_DEBUG "CPU%d IPI_CALL_FUNC_SINGLE\n", this_cpu);
	generic_smp_call_function_single_interrupt();
	break;

	case IPI_CPU_START:
	smp_debug(100, KERN_DEBUG "CPU%d IPI_CPU_START\n", this_cpu);
	break;

	case IPI_CPU_STOP:
	smp_debug(100, KERN_DEBUG "CPU%d IPI_CPU_STOP\n", this_cpu);
	halt_processor();
	break;

	case IPI_CPU_TEST:
	smp_debug(100, KERN_DEBUG "CPU%d is alive!\n", this_cpu);
	break;

	default:
	printk(KERN_CRIT "Unknown IPI num on CPU%d: %lu\n",
	this_cpu, which);
	return IRQ_NONE;
	} /* Switch */
	/* let in any pending interrupts */
	local_irq_enable();
	local_irq_disable();
	} /* while (ops) */
	}
	return IRQ_HANDLED;
	}


	static inline void
	ipi_send(int cpu, enum ipi_message_type op)
	{
	struct cpuinfo_parisc *p = &per_cpu(cpu_data, cpu);
	spinlock_t *lock = &per_cpu(ipi_lock, cpu);
	unsigned long flags;

	spin_lock_irqsave(lock, flags);
	p->pending_ipi \|= 1 << op;
	gsc_writel(IPI_IRQ - CPU_IRQ_BASE, p->hpa);
	spin_unlock_irqrestore(lock, flags);
	}

	static void
	send_IPI_mask(const struct cpumask *mask, enum ipi_message_type op)
	{
	int cpu;

	for_each_cpu(cpu, mask)
	ipi_send(cpu, op);
	}

	static inline void
	send_IPI_single(int dest_cpu, enum ipi_message_type op)
	{
	BUG_ON(dest_cpu == NO_PROC_ID);

	ipi_send(dest_cpu, op);
	}

	static inline void
	send_IPI_allbutself(enum ipi_message_type op)
	{
	int i;

	for_each_online_cpu(i) {
	if (i != smp_processor_id())
	send_IPI_single(i, op);
	}
	}


	inline void
	smp_send_stop(void) { send_IPI_allbutself(IPI_CPU_STOP); }

	static inline void
	smp_send_start(void) { send_IPI_allbutself(IPI_CPU_START); }

	void
	smp_send_reschedule(int cpu) { send_IPI_single(cpu, IPI_RESCHEDULE); }

	void
	smp_send_all_nop(void)
	{
	send_IPI_allbutself(IPI_NOP);
	}

	void arch_send_call_function_ipi_mask(const struct cpumask *mask)
	{
	send_IPI_mask(mask, IPI_CALL_FUNC);
	}

	void arch_send_call_function_single_ipi(int cpu)
	{
	send_IPI_single(cpu, IPI_CALL_FUNC_SINGLE);
	}

	/*
	* Called by secondaries to update state and initialize CPU registers.
	*/
	static void __init
	smp_cpu_init(int cpunum)
	{
	extern int init_per_cpu(int); /* arch/parisc/kernel/processor.c */
	extern void init_IRQ(void); /* arch/parisc/kernel/irq.c */
	extern void start_cpu_itimer(void); /* arch/parisc/kernel/time.c */

	/* Set modes and Enable floating point coprocessor */
	(void) init_per_cpu(cpunum);

	disable_sr_hashing();

	mb();

	/* Well, support 2.4 linux scheme as well. */
	if (cpu_online(cpunum)) {
	extern void machine_halt(void); /* arch/parisc.../process.c */

	printk(KERN_CRIT "CPU#%d already initialized!\n", cpunum);
	machine_halt();
	}

	notify_cpu_starting(cpunum);

	set_cpu_online(cpunum, true);

	/* Initialise the idle task for this CPU */
	atomic_inc(&init_mm.mm_count);
	current->active_mm = &init_mm;
	BUG_ON(current->mm);
	enter_lazy_tlb(&init_mm, current);

	init_IRQ(); /* make sure no IRQs are enabled or pending */
	start_cpu_itimer();
	}


	/*
	* Slaves start using C here. Indirectly called from smp_slave_stext.
	* Do what start_kernel() and main() do for boot strap processor (aka monarch)
	*/
	void __init smp_callin(void)
	{
	int slave_id = cpu_now_booting;

	smp_cpu_init(slave_id);
	preempt_disable();

	flush_cache_all_local(); /* start with known state */
	flush_tlb_all_local(NULL);

	local_irq_enable(); /* Interrupts have been off until now */

	cpu_startup_entry(CPUHP_ONLINE);

	/* NOTREACHED */
	panic("smp_callin() AAAAaaaaahhhh....\n");
	}

	/*
	* Bring one cpu online.
	*/
	int __cpuinit smp_boot_one_cpu(int cpuid, struct task_struct *idle)
	{
	const struct cpuinfo_parisc *p = &per_cpu(cpu_data, cpuid);
	long timeout;

	task_thread_info(idle)->cpu = cpuid;

	/* Let _start know what logical CPU we're booting
	** (offset into init_tasks[],cpu_data[])
	*/
	cpu_now_booting = cpuid;

	/*
	** boot strap code needs to know the task address since
	** it also contains the process stack.
	*/
	smp_init_current_idle_task = idle ;
	mb();

	printk(KERN_INFO "Releasing cpu %d now, hpa=%lx\n", cpuid, p->hpa);

	/*
	** This gets PDC to release the CPU from a very tight loop.
	**
	** From the PA-RISC 2.0 Firmware Architecture Reference Specification:
	** "The MEM_RENDEZ vector specifies the location of OS_RENDEZ which
	** is executed after receiving the rendezvous signal (an interrupt to
	** EIR{0}). MEM_RENDEZ is valid only when it is nonzero and the
	** contents of memory are valid."
	*/
	gsc_writel(TIMER_IRQ - CPU_IRQ_BASE, p->hpa);
	mb();

	/*
	* OK, wait a bit for that CPU to finish staggering about.
	* Slave will set a bit when it reaches smp_cpu_init().
	* Once the "monarch CPU" sees the bit change, it can move on.
	*/
	for (timeout = 0; timeout < 10000; timeout++) {
	if(cpu_online(cpuid)) {
	/* Which implies Slave has started up */
	cpu_now_booting = 0;
	smp_init_current_idle_task = NULL;
	goto alive ;
	}
	udelay(100);
	barrier();
	}
	printk(KERN_CRIT "SMP: CPU:%d is stuck.\n", cpuid);
	return -1;

	alive:
	/* Remember the Slave data */
	smp_debug(100, KERN_DEBUG "SMP: CPU:%d came alive after %ld _us\n",
	cpuid, timeout * 100);
	return 0;
	}

	void __init smp_prepare_boot_cpu(void)
	{
	int bootstrap_processor = per_cpu(cpu_data, 0).cpuid;

	/* Setup BSP mappings */
	printk(KERN_INFO "SMP: bootstrap CPU ID is %d\n", bootstrap_processor);

	set_cpu_online(bootstrap_processor, true);
	set_cpu_present(bootstrap_processor, true);
	}



	/*
	** inventory.c:do_inventory() hasn't yet been run and thus we
	** don't 'discover' the additional CPUs until later.
	*/
	void __init smp_prepare_cpus(unsigned int max_cpus)
	{
	int cpu;

	for_each_possible_cpu(cpu)
	spin_lock_init(&per_cpu(ipi_lock, cpu));

	init_cpu_present(cpumask_of(0));

	parisc_max_cpus = max_cpus;
	if (!max_cpus)
	printk(KERN_INFO "SMP mode deactivated.\n");
	}


	void smp_cpus_done(unsigned int cpu_max)
	{
	return;
	}


	int __cpuinit __cpu_up(unsigned int cpu, struct task_struct *tidle)
	{
	if (cpu != 0 && cpu < parisc_max_cpus)
	smp_boot_one_cpu(cpu, tidle);

	return cpu_online(cpu) ? 0 : -ENOSYS;
	}

	#ifdef CONFIG_PROC_FS
	int __init
	setup_profiling_timer(unsigned int multiplier)
	{
	return -EINVAL;
	}
	#endif