| Glauber Costa | 68a1c3f | 2008-03-03 14:12:42 -0300 | [diff] [blame^] | 1 | #include <linux/init.h> |
| 2 | #include <linux/smp.h> |
| 3 | |
| 4 | #ifdef CONFIG_HOTPLUG_CPU |
| 5 | |
| 6 | int additional_cpus __initdata = -1; |
| 7 | |
| 8 | static __init int setup_additional_cpus(char *s) |
| 9 | { |
| 10 | return s && get_option(&s, &additional_cpus) ? 0 : -EINVAL; |
| 11 | } |
| 12 | early_param("additional_cpus", setup_additional_cpus); |
| 13 | |
| 14 | /* |
| 15 | * cpu_possible_map should be static, it cannot change as cpu's |
| 16 | * are onlined, or offlined. The reason is per-cpu data-structures |
| 17 | * are allocated by some modules at init time, and dont expect to |
| 18 | * do this dynamically on cpu arrival/departure. |
| 19 | * cpu_present_map on the other hand can change dynamically. |
| 20 | * In case when cpu_hotplug is not compiled, then we resort to current |
| 21 | * behaviour, which is cpu_possible == cpu_present. |
| 22 | * - Ashok Raj |
| 23 | * |
| 24 | * Three ways to find out the number of additional hotplug CPUs: |
| 25 | * - If the BIOS specified disabled CPUs in ACPI/mptables use that. |
| 26 | * - The user can overwrite it with additional_cpus=NUM |
| 27 | * - Otherwise don't reserve additional CPUs. |
| 28 | * We do this because additional CPUs waste a lot of memory. |
| 29 | * -AK |
| 30 | */ |
| 31 | __init void prefill_possible_map(void) |
| 32 | { |
| 33 | int i; |
| 34 | int possible; |
| 35 | |
| 36 | if (additional_cpus == -1) { |
| 37 | if (disabled_cpus > 0) |
| 38 | additional_cpus = disabled_cpus; |
| 39 | else |
| 40 | additional_cpus = 0; |
| 41 | } |
| 42 | possible = num_processors + additional_cpus; |
| 43 | if (possible > NR_CPUS) |
| 44 | possible = NR_CPUS; |
| 45 | |
| 46 | printk(KERN_INFO "SMP: Allowing %d CPUs, %d hotplug CPUs\n", |
| 47 | possible, max_t(int, possible - num_processors, 0)); |
| 48 | |
| 49 | for (i = 0; i < possible; i++) |
| 50 | cpu_set(i, cpu_possible_map); |
| 51 | } |
| 52 | #endif |
| 53 | |