2 files changed, 54 insertions, 0 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 856c8b114e71..06377c76e734 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1117,6 +1117,8 @@ and is between 256 and 4096 characters. It is defined in the file
 
         nolapic         [IA-32,APIC] Do not enable or use the local APIC.
 
+        nolapic_timer   [IA-32,APIC] Do not use the local APIC timer.
+
         noltlbs         [PPC] Do not use large page/tlb entries for kernel
                         lowmem mapping on PPC40x.
 
diff --git a/arch/i386/kernel/apic.c b/arch/i386/kernel/apic.c
index 5cff7970911e..36825117835d 100644
--- a/arch/i386/kernel/apic.c
+++ b/arch/i386/kernel/apic.c
@@ -28,6 +28,7 @@
 #include <linux/clockchips.h>
 #include <linux/acpi_pmtmr.h>
 #include <linux/module.h>
+#include <linux/dmi.h>
 
 #include <asm/atomic.h>
 #include <asm/smp.h>
@@ -61,6 +62,8 @@ static int enable_local_apic __initdata = 0;
 
 /* Local APIC timer verification ok */
 static int local_apic_timer_verify_ok;
+/* Disable local APIC timer from the kernel commandline or via dmi quirk */
+static int local_apic_timer_disabled;
 
 /*
  * Debug level, exported for io_apic.c
@@ -266,6 +269,32 @@ static void __devinit setup_APIC_timer(void)
 }
 
 /*
+ * Detect systems with known broken BIOS implementations
+ */
+static int __init lapic_check_broken_bios(struct dmi_system_id *d)
+{
+        printk(KERN_NOTICE "%s detected: disabling lapic timer.\n",
+                       d->ident);
+        local_apic_timer_disabled = 1;
+        return 0;
+}
+
+static struct dmi_system_id __initdata broken_bios_dmi_table[] = {
+        {
+                /*
+                 * BIOS exports only C1 state, but uses deeper power
+                 * modes behind the kernels back.
+                 */
+                  .callback = lapic_check_broken_bios,
+                  .ident = "HP nx6325",
+                  .matches = {
+                        DMI_MATCH(DMI_PRODUCT_NAME, "HP Compaq nx6325"),
+                  },
+         },
+         {}
+};
+
+/*
  * In this functions we calibrate APIC bus clocks to the external timer.
  *
  * We want to do the calibration only once since we want to have local timer
@@ -340,6 +369,22 @@ void __init setup_boot_APIC_clock(void)
         long delta, deltapm;
         int pm_referenced = 0;
 
+        /* Detect know broken systems */
+        dmi_check_system(broken_bios_dmi_table);
+
+        /*
+         * The local apic timer can be disabled via the kernel
+         * commandline or from the dmi quirk above. Register the lapic
+         * timer as a dummy clock event source on SMP systems, so the
+         * broadcast mechanism is used. On UP systems simply ignore it.
+         */
+        if (local_apic_timer_disabled) {
+                /* No broadcast on UP ! */
+                if (num_possible_cpus() > 1)
+                        setup_APIC_timer();
+                return;
+        }
+
         apic_printk(APIC_VERBOSE, "Using local APIC timer interrupts.\n"
                     "calibrating APIC timer ...\n");
 
@@ -1179,6 +1224,13 @@ static int __init parse_nolapic(char *arg)
 }
 early_param("nolapic", parse_nolapic);
 
+static int __init parse_disable_lapic_timer(char *arg)
+{
+        local_apic_timer_disabled = 1;
+        return 0;
+}
+early_param("nolapic_timer", parse_disable_lapic_timer);
+
 static int __init apic_set_verbosity(char *str)
 {
         if (strcmp("debug", str) == 0)