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/*
* Populate sysfs with topology information
*
* Written by: Matthew Dobson, IBM Corporation
* Original Code: Paul Dorwin, IBM Corporation, Patrick Mochel, OSDL
*
* Copyright (C) 2002, IBM Corp.
*
* All rights reserved.
*
* 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.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
* NON INFRINGEMENT. See the GNU General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* Send feedback to <colpatch@us.ibm.com>
*/
#include <linux/interrupt.h>
#include <linux/nodemask.h>
#include <linux/export.h>
#include <linux/mmzone.h>
#include <linux/init.h>
#include <linux/smp.h>
#include <linux/irq.h>
#include <asm/io_apic.h>
#include <asm/cpu.h>
static DEFINE_PER_CPU(struct x86_cpu, cpu_devices);
#ifdef CONFIG_HOTPLUG_CPU
#ifdef CONFIG_BOOTPARAM_HOTPLUG_CPU0
static int cpu0_hotpluggable = 1;
#else
static int cpu0_hotpluggable;
static int __init enable_cpu0_hotplug(char *str)
{
cpu0_hotpluggable = 1;
return 1;
}
__setup("cpu0_hotplug", enable_cpu0_hotplug);
#endif
#ifdef CONFIG_DEBUG_HOTPLUG_CPU0
/*
* This function offlines a CPU as early as possible and allows userspace to
* boot up without the CPU. The CPU can be onlined back by user after boot.
*
* This is only called for debugging CPU offline/online feature.
*/
int _debug_hotplug_cpu(int cpu, int action)
{
int ret;
if (!cpu_is_hotpluggable(cpu))
return -EINVAL;
switch (action) {
case 0:
ret = remove_cpu(cpu);
if (!ret)
pr_info("DEBUG_HOTPLUG_CPU0: CPU %u is now offline\n", cpu);
else
pr_debug("Can't offline CPU%d.\n", cpu);
break;
case 1:
ret = add_cpu(cpu);
if (ret)
pr_debug("Can't online CPU%d.\n", cpu);
break;
default:
ret = -EINVAL;
}
return ret;
}
static int __init debug_hotplug_cpu(void)
{
_debug_hotplug_cpu(0, 0);
return 0;
}
late_initcall_sync(debug_hotplug_cpu);
#endif /* CONFIG_DEBUG_HOTPLUG_CPU0 */
int arch_register_cpu(int num)
{
struct cpuinfo_x86 *c = &cpu_data(num);
/*
* Currently CPU0 is only hotpluggable on Intel platforms. Other
* vendors can add hotplug support later.
* Xen PV guests don't support CPU0 hotplug at all.
*/
if (c->x86_vendor != X86_VENDOR_INTEL ||
boot_cpu_has(X86_FEATURE_XENPV))
cpu0_hotpluggable = 0;
/*
* Two known BSP/CPU0 dependencies: Resume from suspend/hibernate
* depends on BSP. PIC interrupts depend on BSP.
*
* If the BSP dependencies are under control, one can tell kernel to
* enable BSP hotplug. This basically adds a control file and
* one can attempt to offline BSP.
*/
if (num == 0 && cpu0_hotpluggable) {
unsigned int irq;
/*
* We won't take down the boot processor on i386 if some
* interrupts only are able to be serviced by the BSP in PIC.
*/
for_each_active_irq(irq) {
if (!IO_APIC_IRQ(irq) && irq_has_action(irq)) {
cpu0_hotpluggable = 0;
break;
}
}
}
if (num || cpu0_hotpluggable)
per_cpu(cpu_devices, num).cpu.hotpluggable = 1;
return register_cpu(&per_cpu(cpu_devices, num).cpu, num);
}
EXPORT_SYMBOL(arch_register_cpu);
void arch_unregister_cpu(int num)
{
unregister_cpu(&per_cpu(cpu_devices, num).cpu);
}
EXPORT_SYMBOL(arch_unregister_cpu);
#else /* CONFIG_HOTPLUG_CPU */
static int __init arch_register_cpu(int num)
{
return register_cpu(&per_cpu(cpu_devices, num).cpu, num);
}
#endif /* CONFIG_HOTPLUG_CPU */
static int __init topology_init(void)
{
int i;
for_each_present_cpu(i)
arch_register_cpu(i);
return 0;
}
subsys_initcall(topology_init);
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