6 files changed, 25 insertions, 25 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 975f029be25c..17770b456310 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -952,14 +952,10 @@ and is between 256 and 4096 characters. It is defined in the file
                         Format: <1-256>
 
         maxcpus=        [SMP] Maximum number of processors that an SMP kernel
-                        should make use of.
-                        Using "nosmp" or "maxcpus=0" will disable SMP
-                        entirely (the MPS table probe still happens, though).
-                        A command-line option of "maxcpus=<NUM>", where <NUM>
-                        is an integer greater than 0, limits the maximum number
-                        of CPUs activated in SMP mode to <NUM>.
-                        Using "maxcpus=1" on an SMP kernel is the trivial
-                        case of an SMP kernel with only one CPU.
+                        should make use of.  maxcpus=n : n >= 0 limits the
+                        kernel to using 'n' processors.  n=0 is a special case,
+                        it is equivalent to "nosmp", which also disables
+                        the IO APIC.
 
         max_addr=[KMG]  [KNL,BOOT,ia64] All physical memory greater than or
                         equal to this physical address is ignored.
@@ -1184,7 +1180,8 @@ and is between 256 and 4096 characters. It is defined in the file
 
         nosep           [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
 
-        nosmp           [SMP] Tells an SMP kernel to act as a UP kernel.
+        nosmp           [SMP] Tells an SMP kernel to act as a UP kernel,
+                        and disable the IO APIC.  legacy for "maxcpus=0".
 
         nosoftlockup    [KNL] Disable the soft-lockup detector.
 
diff --git a/arch/i386/kernel/io_apic.c b/arch/i386/kernel/io_apic.c
index 4b8a8da4b2e0..e2f4a1c68547 100644
--- a/arch/i386/kernel/io_apic.c
+++ b/arch/i386/kernel/io_apic.c
@@ -754,14 +754,6 @@ static int pirq_entries [MAX_PIRQS];
 static int pirqs_enabled;
 int skip_ioapic_setup;
 
-static int __init ioapic_setup(char *str)
-{
-        skip_ioapic_setup = 1;
-        return 1;
-}
-
-__setup("noapic", ioapic_setup);
-
 static int __init ioapic_pirq_setup(char *str)
 {
         int i, max;
diff --git a/arch/x86_64/kernel/io_apic.c b/arch/x86_64/kernel/io_apic.c
index f57f8b901912..966fa1062491 100644
--- a/arch/x86_64/kernel/io_apic.c
+++ b/arch/x86_64/kernel/io_apic.c
@@ -397,14 +397,12 @@ static void clear_IO_APIC (void)
 int skip_ioapic_setup;
 int ioapic_force;
 
-/* dummy parsing: see setup.c */
-
-static int __init disable_ioapic_setup(char *str)
+static int __init parse_noapic(char *str)
 {
-        skip_ioapic_setup = 1;
+        disable_ioapic_setup();
         return 0;
 }
-early_param("noapic", disable_ioapic_setup);
+early_param("noapic", parse_noapic);
 
 /* Actually the next is obsolete, but keep it for paranoid reasons -AK */
 static int __init disable_timer_pin_setup(char *arg)
diff --git a/include/asm-i386/io_apic.h b/include/asm-i386/io_apic.h
index 340764076d5f..dbe734ddf2af 100644
--- a/include/asm-i386/io_apic.h
+++ b/include/asm-i386/io_apic.h
@@ -150,7 +150,6 @@ extern int (*ioapic_renumber_irq)(int ioapic, int irq);
 
 #else  /* !CONFIG_X86_IO_APIC */
 #define io_apic_assign_pci_irqs 0
-static inline void disable_ioapic_setup(void) { }
 #endif
 
 #endif
diff --git a/include/asm-x86_64/io_apic.h b/include/asm-x86_64/io_apic.h
index 969d225a9350..d9f2e54324d5 100644
--- a/include/asm-x86_64/io_apic.h
+++ b/include/asm-x86_64/io_apic.h
@@ -109,6 +109,12 @@ extern int mpc_default_type;
 /* 1 if "noapic" boot option passed */
 extern int skip_ioapic_setup;
 
+static inline void disable_ioapic_setup(void)
+{
+        skip_ioapic_setup = 1;
+}
+
+
 /*
  * If we use the IO-APIC for IRQ routing, disable automatic
  * assignment of PCI IRQ's.
diff --git a/init/main.c b/init/main.c
index d3bcb3b11620..cc0653ec081d 100644
--- a/init/main.c
+++ b/init/main.c
@@ -146,9 +146,14 @@ static unsigned int __initdata max_cpus = NR_CPUS;
  * greater than 0, limits the maximum number of CPUs activated in
  * SMP mode to <NUM>.
  */
+#ifndef CONFIG_X86_IO_APIC
+static inline void disable_ioapic_setup(void) {};
+#endif
+
 static int __init nosmp(char *str)
 {
         max_cpus = 0;
+        disable_ioapic_setup();
         return 0;
 }
 
@@ -157,10 +162,13 @@ early_param("nosmp", nosmp);
 static int __init maxcpus(char *str)
 {
         get_option(&str, &max_cpus);
-        return 1;
+        if (max_cpus == 0)
+                disable_ioapic_setup();
+
+        return 0;
 }
 
-__setup("maxcpus=", maxcpus);
+early_param("maxcpus=", maxcpus);
 #else
 #define max_cpus NR_CPUS
 #endif