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TOMOYO Linux Cross Reference
Linux/arch/x86/kernel/topology.c

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  1 /*
  2  * Populate sysfs with topology information
  3  *
  4  * Written by: Matthew Dobson, IBM Corporation
  5  * Original Code: Paul Dorwin, IBM Corporation, Patrick Mochel, OSDL
  6  *
  7  * Copyright (C) 2002, IBM Corp.
  8  *
  9  * All rights reserved.
 10  *
 11  * This program is free software; you can redistribute it and/or modify
 12  * it under the terms of the GNU General Public License as published by
 13  * the Free Software Foundation; either version 2 of the License, or
 14  * (at your option) any later version.
 15  *
 16  * This program is distributed in the hope that it will be useful, but
 17  * WITHOUT ANY WARRANTY; without even the implied warranty of
 18  * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
 19  * NON INFRINGEMENT.  See the GNU General Public License for more
 20  * details.
 21  *
 22  * You should have received a copy of the GNU General Public License
 23  * along with this program; if not, write to the Free Software
 24  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 25  *
 26  * Send feedback to <colpatch@us.ibm.com>
 27  */
 28 #include <linux/interrupt.h>
 29 #include <linux/nodemask.h>
 30 #include <linux/export.h>
 31 #include <linux/mmzone.h>
 32 #include <linux/init.h>
 33 #include <linux/smp.h>
 34 #include <linux/irq.h>
 35 #include <asm/io_apic.h>
 36 #include <asm/cpu.h>
 37 
 38 static DEFINE_PER_CPU(struct x86_cpu, cpu_devices);
 39 
 40 #ifdef CONFIG_HOTPLUG_CPU
 41 
 42 #ifdef CONFIG_BOOTPARAM_HOTPLUG_CPU0
 43 static int cpu0_hotpluggable = 1;
 44 #else
 45 static int cpu0_hotpluggable;
 46 static int __init enable_cpu0_hotplug(char *str)
 47 {
 48         cpu0_hotpluggable = 1;
 49         return 1;
 50 }
 51 
 52 __setup("cpu0_hotplug", enable_cpu0_hotplug);
 53 #endif
 54 
 55 #ifdef CONFIG_DEBUG_HOTPLUG_CPU0
 56 /*
 57  * This function offlines a CPU as early as possible and allows userspace to
 58  * boot up without the CPU. The CPU can be onlined back by user after boot.
 59  *
 60  * This is only called for debugging CPU offline/online feature.
 61  */
 62 int _debug_hotplug_cpu(int cpu, int action)
 63 {
 64         int ret;
 65 
 66         if (!cpu_is_hotpluggable(cpu))
 67                 return -EINVAL;
 68 
 69         switch (action) {
 70         case 0:
 71                 ret = remove_cpu(cpu);
 72                 if (!ret)
 73                         pr_info("DEBUG_HOTPLUG_CPU0: CPU %u is now offline\n", cpu);
 74                 else
 75                         pr_debug("Can't offline CPU%d.\n", cpu);
 76                 break;
 77         case 1:
 78                 ret = add_cpu(cpu);
 79                 if (ret)
 80                         pr_debug("Can't online CPU%d.\n", cpu);
 81 
 82                 break;
 83         default:
 84                 ret = -EINVAL;
 85         }
 86 
 87         return ret;
 88 }
 89 
 90 static int __init debug_hotplug_cpu(void)
 91 {
 92         _debug_hotplug_cpu(0, 0);
 93         return 0;
 94 }
 95 
 96 late_initcall_sync(debug_hotplug_cpu);
 97 #endif /* CONFIG_DEBUG_HOTPLUG_CPU0 */
 98 
 99 int arch_register_cpu(int num)
100 {
101         struct cpuinfo_x86 *c = &cpu_data(num);
102 
103         /*
104          * Currently CPU0 is only hotpluggable on Intel platforms. Other
105          * vendors can add hotplug support later.
106          * Xen PV guests don't support CPU0 hotplug at all.
107          */
108         if (c->x86_vendor != X86_VENDOR_INTEL ||
109             boot_cpu_has(X86_FEATURE_XENPV))
110                 cpu0_hotpluggable = 0;
111 
112         /*
113          * Two known BSP/CPU0 dependencies: Resume from suspend/hibernate
114          * depends on BSP. PIC interrupts depend on BSP.
115          *
116          * If the BSP depencies are under control, one can tell kernel to
117          * enable BSP hotplug. This basically adds a control file and
118          * one can attempt to offline BSP.
119          */
120         if (num == 0 && cpu0_hotpluggable) {
121                 unsigned int irq;
122                 /*
123                  * We won't take down the boot processor on i386 if some
124                  * interrupts only are able to be serviced by the BSP in PIC.
125                  */
126                 for_each_active_irq(irq) {
127                         if (!IO_APIC_IRQ(irq) && irq_has_action(irq)) {
128                                 cpu0_hotpluggable = 0;
129                                 break;
130                         }
131                 }
132         }
133         if (num || cpu0_hotpluggable)
134                 per_cpu(cpu_devices, num).cpu.hotpluggable = 1;
135 
136         return register_cpu(&per_cpu(cpu_devices, num).cpu, num);
137 }
138 EXPORT_SYMBOL(arch_register_cpu);
139 
140 void arch_unregister_cpu(int num)
141 {
142         unregister_cpu(&per_cpu(cpu_devices, num).cpu);
143 }
144 EXPORT_SYMBOL(arch_unregister_cpu);
145 #else /* CONFIG_HOTPLUG_CPU */
146 
147 static int __init arch_register_cpu(int num)
148 {
149         return register_cpu(&per_cpu(cpu_devices, num).cpu, num);
150 }
151 #endif /* CONFIG_HOTPLUG_CPU */
152 
153 static int __init topology_init(void)
154 {
155         int i;
156 
157 #ifdef CONFIG_NUMA
158         for_each_online_node(i)
159                 register_one_node(i);
160 #endif
161 
162         for_each_present_cpu(i)
163                 arch_register_cpu(i);
164 
165         return 0;
166 }
167 subsys_initcall(topology_init);
168 

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