diff --git a/bios/rombios32.c b/bios/rombios32.c
index 314df94..65d6207 100755
--- a/bios/rombios32.c
+++ b/bios/rombios32.c
@@ -1181,6 +1181,14 @@ struct madt_io_apic
 			  * lines start */
 };
 
+struct madt_interrupt_source_override {
+	APIC_HEADER_DEF
+	uint8_t bus;
+	uint8_t source;
+	uint32_t gsi;
+	uint16_t flags;
+} __attribute__((__packed__));
+
 #include "acpi-dsdt.hex"
 
 static inline uint16_t cpu_to_le16(uint16_t x)
@@ -1273,7 +1281,8 @@ void acpi_bios_init(void)
     madt_addr = addr;
     madt_size = sizeof(*madt) + 
         sizeof(struct madt_processor_apic) * smp_cpus +
-        sizeof(struct madt_io_apic);
+        sizeof(struct madt_io_apic) +
+	sizeof(struct madt_interrupt_source_override) * 4;
     madt = (void *)(addr);
     addr += madt_size;
 
@@ -1335,6 +1344,8 @@ void acpi_bios_init(void)
     {
         struct madt_processor_apic *apic;
         struct madt_io_apic *io_apic;
+        struct madt_interrupt_source_override *iso;
+	static int pci_irq[4] = { 5, 9, 10, 11 };
 
         memset(madt, 0, madt_size);
         madt->local_apic_address = cpu_to_le32(0xfee00000);
@@ -1354,6 +1365,17 @@ void acpi_bios_init(void)
         io_apic->io_apic_id = smp_cpus;
         io_apic->address = cpu_to_le32(0xfec00000);
         io_apic->interrupt = cpu_to_le32(0);
+	io_apic++;
+	iso = (void *)io_apic;
+	for (i = 0; i < 4; ++i) {
+	    iso->type = APIC_XRUPT_OVERRIDE;
+	    iso->length = sizeof(*iso);
+	    iso->bus = 0;
+	    iso->source = pci_irq[i];
+	    iso->gsi = cpu_to_le32(iso->source);
+	    iso->flags = cpu_to_le16(0xd); // active high level trigger
+	    ++iso;
+	}
 
         acpi_build_table_header((struct acpi_table_header *)madt, 
                                 "APIC", madt_size);