[PATCH 0/1] 2.6.17-rc5 patch for HPET operation on NVIDIA platforms

["Andy Currid" <ACurrid@nvidia.com>]

This patch fixes a kernel panic during boot that occurs on NVIDIA
platforms that have
HPET enabled. When HPET is enabled, the standard timer IRQ is routed to
IOAPIC pin 2
and is advertised as such in the ACPI APIC table - but an earlier
workaround in the
kernel was ignoring this override. The fix is to honor timer IRQ
overrides from ACPI
when HPET is detected on an NVIDIA platform.

64-bit kernel patch:

Signed-off-by: Andy Currid <acurrid@nvidia.com>

diff -u linux-2.6.17-rc5/arch/x86_64/kernel/io_apic.c
linux-2.6.17-rc5-patch/arch/x86_64/kernel/io_apic.c 
--- linux-2.6.17-rc5/arch/x86_64/kernel/io_apic.c	2006-05-27
15:38:26.000000000 -0700
+++ linux-2.6.17-rc5-patch/arch/x86_64/kernel/io_apic.c	2006-05-27
16:33:55.000000000 -0700
@@ -271,6 +271,18 @@
 #include <linux/pci_ids.h>
 #include <linux/pci.h>
 
+
+#ifdef CONFIG_ACPI
+
+static int nvidia_hpet_detected __initdata;
+
+static int __init nvidia_hpet_check(unsigned long phys, unsigned long
size)
+{
+	nvidia_hpet_detected = 1;
+	return 0;
+}
+#endif
+
 /* Temporary Hack. Nvidia and VIA boards currently only work with
IO-APIC
    off. Check for an Nvidia or VIA PCI bridge and turn it off.
    Use pci direct infrastructure because this runs before the PCI
subsystem. 
@@ -317,11 +329,15 @@
 					return;
 				case PCI_VENDOR_ID_NVIDIA:
 #ifdef CONFIG_ACPI
-					/* All timer overrides on Nvidia
-				           seem to be wrong. Skip them.
*/
-					acpi_skip_timer_override = 1;
-					printk(KERN_INFO 
-	     "Nvidia board detected. Ignoring ACPI timer override.\n");
+					/* All timer overrides on Nvidia
are wrong unless HPET
+				           is enabled. */
+					nvidia_hpet_detected = 0;
+					acpi_table_parse(ACPI_HPET,
nvidia_hpet_check);
+					if (nvidia_hpet_detected == 0) {
+						acpi_skip_timer_override
= 1;
+						printk(KERN_INFO 
+		     "Nvidia board detected. Ignoring ACPI timer
override.\n");
+					}
 #endif
 					/* RED-PEN skip them on mptables
too? */
 					return;

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