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adjust nosmp handling 

Especially when !CONFIG_HOTPLUG_CPU, avoid needlessy allocating resources for
CPUs that can never become available.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Jan Beulich 2007-07-15 23:41:07 -07:00 committed by Linus Torvalds
parent 98c0d07cbf
commit 8b3b295502
1 changed files with 27 additions and 15 deletions
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42
init/main.c
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@ -132,20 +132,9 @@ static char *static_command_line;
static char *execute_command;
static char *ramdisk_execute_command;
#ifdef CONFIG_SMP
/* Setup configured maximum number of CPUs to activate */
static unsigned int max_cpus = NR_CPUS;
/*
* If set, this is an indication to the drivers that reset the underlying
* device before going ahead with the initialization otherwise driver might
* rely on the BIOS and skip the reset operation.
*
* This is useful if kernel is booting in an unreliable environment.
* For ex. kdump situaiton where previous kernel has crashed, BIOS has been
* skipped and devices will be in unknown state.
*/
unsigned int reset_devices;
EXPORT_SYMBOL(reset_devices);
static unsigned int __initdata max_cpus = NR_CPUS;
/*
* Setup routine for controlling SMP activation
@ -160,10 +149,10 @@ EXPORT_SYMBOL(reset_devices);
static int __init nosmp(char *str)
{
max_cpus = 0;
return 1;
return 0;
}
__setup("nosmp", nosmp);
early_param("nosmp", nosmp);
static int __init maxcpus(char *str)
{
@ -172,6 +161,21 @@ static int __init maxcpus(char *str)
}
__setup("maxcpus=", maxcpus);
#else
#define max_cpus NR_CPUS
#endif
/*
* If set, this is an indication to the drivers that reset the underlying
* device before going ahead with the initialization otherwise driver might
* rely on the BIOS and skip the reset operation.
*
* This is useful if kernel is booting in an unreliable environment.
* For ex. kdump situaiton where previous kernel has crashed, BIOS has been
* skipped and devices will be in unknown state.
*/
unsigned int reset_devices;
EXPORT_SYMBOL(reset_devices);
static int __init set_reset_devices(char *str)
{
@ -385,6 +389,10 @@ static void __init smp_init(void)
{
unsigned int cpu;
#ifndef CONFIG_HOTPLUG_CPU
cpu_possible_map = cpu_present_map;
#endif
/* FIXME: This should be done in userspace --RR */
for_each_present_cpu(cpu) {
if (num_online_cpus() >= max_cpus)
@ -529,6 +537,10 @@ asmlinkage void __init start_kernel(void)
setup_arch(&command_line);
setup_command_line(command_line);
unwind_setup();
#ifndef CONFIG_HOTPLUG_CPU
if (max_cpus < 2)
cpu_possible_map = cpu_online_map;
#endif
setup_per_cpu_areas();
smp_prepare_boot_cpu(); /* arch-specific boot-cpu hooks */