The local APIC timer stops to work in deeper C-States. This is handled
by the ACPI code and a broadcast mechanism in the clockevents / tick
managment code.
Some systems do not expose the deeper C-States to the kernel, but switch
into deeper C-States behind the kernels back. This delays the local apic
timer interrupts for ever and makes the systems unusable.
Add a command line option to disable the local apic timer and a dmi
quirk for known broken systems.
Signed-off-by: Thomas Gleixner <[EMAIL PROTECTED]>
diff --git a/Documentation/kernel-parameters.txt
b/Documentation/kernel-parameters.txt
index 856c8b1..06377c7 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 5cff797..3682511 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)
-
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