--- linux-2.6.21.3.orig/arch/i386/kernel/io_apic.c	2007-06-02 14:17:10.000000000 +0000
+++ linux-2.6.21.3/arch/i386/kernel/io_apic.c	2007-06-02 22:24:44.000000000 +0000
@@ -35,6 +35,7 @@
 #include <linux/msi.h>
 #include <linux/htirq.h>
 #include <linux/freezer.h>
+#include <linux/dmi.h>
 
 #include <asm/io.h>
 #include <asm/smp.h>
@@ -44,6 +45,7 @@
 #include <asm/nmi.h>
 #include <asm/msidef.h>
 #include <asm/hypertransport.h>
+#include <asm/acpi.h>
 
 #include <mach_apic.h>
 #include <mach_apicdef.h>
@@ -98,6 +100,33 @@
 	unsigned int data;
 };
 
+static int __init disable_gx240_ioapic(struct dmi_system_id *d)
+{
+	/* Disable IO-APIC only if ACPI is disabled */
+	if (acpi_disabled) {
+		printk(KERN_WARNING "%s detected... Disabling IO-APIC\n", d->ident);
+		skip_ioapic_setup = 1;
+	}
+	return(0);
+}
+
+static struct dmi_system_id __initdata ioapic_blacklist_dmi_table[] = {
+	{
+		.callback = disable_gx240_ioapic,
+		.ident = "Dell OptiPlex GX240",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Dell Computer Corporation"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex GX240"),
+		},
+	},
+	{ }
+};
+
+void __init check_ioapic_blacklist(void) {
+	printk(KERN_INFO "Checking for IO-APIC blacklisted systems...\n");
+	dmi_check_system(ioapic_blacklist_dmi_table);
+}
+
 static __attribute_const__ struct io_apic __iomem *io_apic_base(int idx)
 {
 	return (void __iomem *) __fix_to_virt(FIX_IO_APIC_BASE_0 + idx)
--- linux-2.6.21.3.orig/arch/i386/kernel/setup.c	2007-06-02 14:17:10.000000000 +0000
+++ linux-2.6.21.3/arch/i386/kernel/setup.c	2007-06-02 22:39:46.000000000 +0000
@@ -124,6 +124,7 @@
 #endif
 
 extern void early_cpu_init(void);
+extern void check_ioapic_blacklist(void);
 extern int root_mountflags;
 
 unsigned long saved_videomode;
@@ -642,6 +643,11 @@
 			"CONFIG_X86_GENERICARCH or CONFIG_X86_BIGSMP.\n");
 #endif
 #endif
+
+#ifdef CONFIG_X86_IO_APIC
+	check_ioapic_blacklist(); /* This must be after acpi_boot_init */
+#endif
+
 #ifdef CONFIG_X86_LOCAL_APIC
 	if (smp_found_config)
 		get_smp_config();