---

yaml
---
r: 185163
b: refs/heads/master
c: 2b633e3
h: refs/heads/master
i:
  185161: 64ee069
  185159: 4145c3f
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 6738762d73a237ec322b04d8b9d55c8fd5d84713
+refs/heads/master: 2b633e3fac5efada088b57d31e65401f22bcc18f

trunk/Documentation/kernel-parameters.txt

@@ -1772,6 +1772,12 @@ and is between 256 and 4096 characters. It is defined in the file
 			purges which is reported from either PAL_VM_SUMMARY or
 			SAL PALO.
 
+	nr_cpus=	[SMP] Maximum number of processors that	an SMP kernel
+			could support.  nr_cpus=n : n >= 1 limits the kernel to
+			supporting 'n' processors. Later in runtime you can not
+			use hotplug cpu feature to put more cpu back to online.
+			just like you compile the kernel NR_CPUS=n
+
 	nr_uarts=	[SERIAL] maximum number of UARTs to be registered.
 
 	numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.

trunk/arch/ia64/kernel/acpi.c

@@ -881,8 +881,8 @@ __init void prefill_possible_map(void)
 
 	possible = available_cpus + additional_cpus;
 
-	if (possible > NR_CPUS)
-		possible = NR_CPUS;
+	if (possible > nr_cpu_ids)
+		possible = nr_cpu_ids;
 
 	printk(KERN_INFO "SMP: Allowing %d CPUs, %d hotplug CPUs\n",
 		possible, max((possible - available_cpus), 0));

trunk/arch/x86/kernel/smpboot.c

@@ -1213,11 +1213,12 @@ __init void prefill_possible_map(void)
 
 	total_cpus = max_t(int, possible, num_processors + disabled_cpus);
 
-	if (possible > CONFIG_NR_CPUS) {
+	/* nr_cpu_ids could be reduced via nr_cpus= */
+	if (possible > nr_cpu_ids) {
 		printk(KERN_WARNING
 			"%d Processors exceeds NR_CPUS limit of %d\n",
-			possible, CONFIG_NR_CPUS);
-		possible = CONFIG_NR_CPUS;
+			possible, nr_cpu_ids);
+		possible = nr_cpu_ids;
 	}
 
 	printk(KERN_INFO "SMP: Allowing %d CPUs, %d hotplug CPUs\n",

trunk/drivers/acpi/numa.c

@@ -279,9 +279,9 @@ int __init acpi_numa_init(void)
 	/* SRAT: Static Resource Affinity Table */
 	if (!acpi_table_parse(ACPI_SIG_SRAT, acpi_parse_srat)) {
 		acpi_table_parse_srat(ACPI_SRAT_TYPE_X2APIC_CPU_AFFINITY,
-				      acpi_parse_x2apic_affinity, NR_CPUS);
+				     acpi_parse_x2apic_affinity, nr_cpu_ids);
 		acpi_table_parse_srat(ACPI_SRAT_TYPE_CPU_AFFINITY,
-				      acpi_parse_processor_affinity, NR_CPUS);
+				     acpi_parse_processor_affinity, nr_cpu_ids);
 		ret = acpi_table_parse_srat(ACPI_SRAT_TYPE_MEMORY_AFFINITY,
 					    acpi_parse_memory_affinity,
 					    NR_NODE_MEMBLKS);

trunk/init/main.c

@@ -149,6 +149,20 @@ static int __init nosmp(char *str)
 
 early_param("nosmp", nosmp);
 
+/* this is hard limit */
+static int __init nrcpus(char *str)
+{
+	int nr_cpus;
+
+	get_option(&str, &nr_cpus);
+	if (nr_cpus > 0 && nr_cpus < nr_cpu_ids)
+		nr_cpu_ids = nr_cpus;
+
+	return 0;
+}
+
+early_param("nr_cpus", nrcpus);
+
 static int __init maxcpus(char *str)
 {
 	get_option(&str, &setup_max_cpus);