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/nodemask.h> 29 #include <linux/export.h> 30 #include <linux/mmzone.h> 31 #include <linux/init.h> 32 #include <linux/smp.h> 33 #include <linux/irq.h> 34 #include <asm/cpu.h> 35 36 static DEFINE_PER_CPU(struct x86_cpu, cpu_devices); 37 38 #ifdef CONFIG_HOTPLUG_CPU 39 40 #ifdef CONFIG_BOOTPARAM_HOTPLUG_CPU0 41 static int cpu0_hotpluggable = 1; 42 #else 43 static int cpu0_hotpluggable; 44 static int __init enable_cpu0_hotplug(char *str) 45 { 46 cpu0_hotpluggable = 1; 47 return 1; 48 } 49 50 __setup("cpu0_hotplug", enable_cpu0_hotplug); 51 #endif 52 53 #ifdef CONFIG_DEBUG_HOTPLUG_CPU0 54 /* 55 * This function offlines a CPU as early as possible and allows userspace to 56 * boot up without the CPU. The CPU can be onlined back by user after boot. 57 * 58 * This is only called for debugging CPU offline/online feature. 59 */ 60 int _debug_hotplug_cpu(int cpu, int action) 61 { 62 int ret; 63 64 if (!cpu_is_hotpluggable(cpu)) 65 return -EINVAL; 66 67 switch (action) { 68 case 0: 69 ret = remove_cpu(cpu); 70 if (!ret) 71 pr_info("DEBUG_HOTPLUG_CPU0: CPU %u is now offline\n", cpu); 72 else 73 pr_debug("Can't offline CPU%d.\n", cpu); 74 break; 75 case 1: 76 ret = add_cpu(cpu); 77 if (ret) 78 pr_debug("Can't online CPU%d.\n", cpu); 79 80 break; 81 default: 82 ret = -EINVAL; 83 } 84 85 return ret; 86 } 87 88 static int __init debug_hotplug_cpu(void) 89 { 90 _debug_hotplug_cpu(0, 0); 91 return 0; 92 } 93 94 late_initcall_sync(debug_hotplug_cpu); 95 #endif /* CONFIG_DEBUG_HOTPLUG_CPU0 */ 96 97 int arch_register_cpu(int num) 98 { 99 struct cpuinfo_x86 *c = &cpu_data(num); 100 101 /* 102 * Currently CPU0 is only hotpluggable on Intel platforms. Other 103 * vendors can add hotplug support later. 104 * Xen PV guests don't support CPU0 hotplug at all. 105 */ 106 if (c->x86_vendor != X86_VENDOR_INTEL || 107 boot_cpu_has(X86_FEATURE_XENPV)) 108 cpu0_hotpluggable = 0; 109 110 /* 111 * Two known BSP/CPU0 dependencies: Resume from suspend/hibernate 112 * depends on BSP. PIC interrupts depend on BSP. 113 * 114 * If the BSP depencies are under control, one can tell kernel to 115 * enable BSP hotplug. This basically adds a control file and 116 * one can attempt to offline BSP. 117 */ 118 if (num == 0 && cpu0_hotpluggable) { 119 unsigned int irq; 120 /* 121 * We won't take down the boot processor on i386 if some 122 * interrupts only are able to be serviced by the BSP in PIC. 123 */ 124 for_each_active_irq(irq) { 125 if (!IO_APIC_IRQ(irq) && irq_has_action(irq)) { 126 cpu0_hotpluggable = 0; 127 break; 128 } 129 } 130 } 131 if (num || cpu0_hotpluggable) 132 per_cpu(cpu_devices, num).cpu.hotpluggable = 1; 133 134 return register_cpu(&per_cpu(cpu_devices, num).cpu, num); 135 } 136 EXPORT_SYMBOL(arch_register_cpu); 137 138 void arch_unregister_cpu(int num) 139 { 140 unregister_cpu(&per_cpu(cpu_devices, num).cpu); 141 } 142 EXPORT_SYMBOL(arch_unregister_cpu); 143 #else /* CONFIG_HOTPLUG_CPU */ 144 145 static int __init arch_register_cpu(int num) 146 { 147 return register_cpu(&per_cpu(cpu_devices, num).cpu, num); 148 } 149 #endif /* CONFIG_HOTPLUG_CPU */ 150 151 static int __init topology_init(void) 152 { 153 int i; 154 155 #ifdef CONFIG_NUMA 156 for_each_online_node(i) 157 register_one_node(i); 158 #endif 159 160 for_each_present_cpu(i) 161 arch_register_cpu(i); 162 163 return 0; 164 } 165 subsys_initcall(topology_init); 166