[PATCH] Fix 'pci=noacpi' with buggy ACPI BIOSes

From: Thomas Schlichter <schlicht@uni-mannheim.de>

Make the `pci=noacpi' command line option work correctly.  It fixes
interrupt routing probems for (at least 3) people with broken ACPI BIOSes.

arch/i386/kernel/acpi/boot.c

@@ -41,6 +41,7 @@
 #define PREFIX			"ACPI: "
 
 extern int acpi_disabled;
+extern int acpi_irq;
 extern int acpi_ht;
 
 int acpi_lapic = 0;
@@ -407,7 +408,7 @@ acpi_boot_init (void)
 	 * If MPS is present, it will handle them,
 	 * otherwise the system will stay in PIC mode
 	 */
-	if (acpi_disabled) {
+	if (acpi_disabled || !acpi_irq) {
 		return 1;
         }
 

arch/i386/kernel/setup.c

@@ -71,6 +71,7 @@ EXPORT_SYMBOL_GPL(mmu_cr4_features);
 EXPORT_SYMBOL(acpi_disabled);
 
 #ifdef	CONFIG_ACPI_BOOT
+	int acpi_irq __initdata = 1;	/* enable IRQ */
 	int acpi_ht __initdata = 1;	/* enable HT */
 #endif
 
@@ -544,6 +545,11 @@ static void __init parse_cmdline_early (char ** cmdline_p)
 			if (!acpi_force) acpi_disabled = 1;
 		}
 
+		/* "pci=noacpi" disables ACPI interrupt routing */
+		else if (!memcmp(from, "pci=noacpi", 10)) {
+			acpi_irq = 0;
+		}
+
 #ifdef CONFIG_X86_LOCAL_APIC
 		/* disable IO-APIC */
 		else if (!memcmp(from, "noapic", 6))