diff --git a/hw/hpet.c b/hw/hpet.c
index 82a9a21978..91ebb75551 100644
--- a/hw/hpet.c
+++ b/hw/hpet.c
@@ -713,7 +713,6 @@ static int hpet_init(SysBusDevice *dev)
     s->capability |= (s->num_timers - 1) << HPET_ID_NUM_TIM_SHIFT;
     s->capability |= ((HPET_CLK_PERIOD) << 32);
 
-    isa_reserve_irq(RTC_ISA_IRQ);
     qdev_init_gpio_in(&dev->qdev, hpet_handle_rtc_irq, 1);
 
     /* HPET Area */
diff --git a/hw/i8254.c b/hw/i8254.c
index 680caabf3c..eaf5d3e174 100644
--- a/hw/i8254.c
+++ b/hw/i8254.c
@@ -514,7 +514,7 @@ static int pit_initfn(ISADevice *dev)
     s = &pit->channels[0];
     /* the timer 0 is connected to an IRQ */
     s->irq_timer = qemu_new_timer(vm_clock, pit_irq_timer, s);
-    s->irq = isa_reserve_irq(pit->irq);
+    s->irq = isa_get_irq(pit->irq);
 
     register_ioport_write(pit->iobase, 4, 1, pit_ioport_write, pit);
     register_ioport_read(pit->iobase, 3, 1, pit_ioport_read, pit);
diff --git a/hw/ide/piix.c b/hw/ide/piix.c
index d4289af9c4..c3496448c3 100644
--- a/hw/ide/piix.c
+++ b/hw/ide/piix.c
@@ -122,7 +122,7 @@ static void pci_piix_init_ports(PCIIDEState *d) {
     for (i = 0; i < 2; i++) {
         ide_bus_new(&d->bus[i], &d->dev.qdev, i);
         ide_init_ioport(&d->bus[i], port_info[i].iobase, port_info[i].iobase2);
-        ide_init2(&d->bus[i], isa_reserve_irq(port_info[i].isairq));
+        ide_init2(&d->bus[i], isa_get_irq(port_info[i].isairq));
 
         bmdma_init(&d->bus[i], &d->bmdma[i]);
         d->bmdma[i].bus = &d->bus[i];
diff --git a/hw/ide/via.c b/hw/ide/via.c
index 0e906797cd..04f3290960 100644
--- a/hw/ide/via.c
+++ b/hw/ide/via.c
@@ -145,7 +145,7 @@ static void vt82c686b_init_ports(PCIIDEState *d) {
     for (i = 0; i < 2; i++) {
         ide_bus_new(&d->bus[i], &d->dev.qdev, i);
         ide_init_ioport(&d->bus[i], port_info[i].iobase, port_info[i].iobase2);
-        ide_init2(&d->bus[i], isa_reserve_irq(port_info[i].isairq));
+        ide_init2(&d->bus[i], isa_get_irq(port_info[i].isairq));
 
         bmdma_init(&d->bus[i], &d->bmdma[i]);
         d->bmdma[i].bus = &d->bus[i];
diff --git a/hw/isa-bus.c b/hw/isa-bus.c
index 6f349a574a..d07aa410f7 100644
--- a/hw/isa-bus.c
+++ b/hw/isa-bus.c
@@ -25,7 +25,6 @@
 struct ISABus {
     BusState qbus;
     qemu_irq *irqs;
-    uint32_t assigned;
 };
 static ISABus *isabus;
 target_phys_addr_t isa_mem_base = 0;
@@ -61,33 +60,24 @@ void isa_bus_irqs(qemu_irq *irqs)
 }
 
 /*
- * isa_reserve_irq() reserves the ISA irq and returns the corresponding
- * qemu_irq entry for the i8259.
+ * isa_get_irq() returns the corresponding qemu_irq entry for the i8259.
  *
  * This function is only for special cases such as the 'ferr', and
  * temporary use for normal devices until they are converted to qdev.
  */
-qemu_irq isa_reserve_irq(int isairq)
+qemu_irq isa_get_irq(int isairq)
 {
     if (isairq < 0 || isairq > 15) {
         hw_error("isa irq %d invalid", isairq);
     }
-    if (isabus->assigned & (1 << isairq)) {
-        hw_error("isa irq %d already assigned", isairq);
-    }
-    isabus->assigned |= (1 << isairq);
     return isabus->irqs[isairq];
 }
 
 void isa_init_irq(ISADevice *dev, qemu_irq *p, int isairq)
 {
     assert(dev->nirqs < ARRAY_SIZE(dev->isairq));
-    if (isabus->assigned & (1 << isairq)) {
-        hw_error("isa irq %d already assigned", isairq);
-    }
-    isabus->assigned |= (1 << isairq);
     dev->isairq[dev->nirqs] = isairq;
-    *p = isabus->irqs[isairq];
+    *p = isa_get_irq(isairq);
     dev->nirqs++;
 }
 
diff --git a/hw/isa.h b/hw/isa.h
index e26abfa063..d2b6126602 100644
--- a/hw/isa.h
+++ b/hw/isa.h
@@ -26,7 +26,7 @@ struct ISADeviceInfo {
 
 ISABus *isa_bus_new(DeviceState *dev);
 void isa_bus_irqs(qemu_irq *irqs);
-qemu_irq isa_reserve_irq(int isairq);
+qemu_irq isa_get_irq(int isairq);
 void isa_init_irq(ISADevice *dev, qemu_irq *p, int isairq);
 void isa_init_ioport(ISADevice *dev, uint16_t ioport);
 void isa_init_ioport_range(ISADevice *dev, uint16_t start, uint16_t length);
diff --git a/hw/mips_malta.c b/hw/mips_malta.c
index ca6c6d7063..d8baa6d7e3 100644
--- a/hw/mips_malta.c
+++ b/hw/mips_malta.c
@@ -919,7 +919,7 @@ void mips_malta_init (ram_addr_t ram_size,
     isa_bus_irqs(i8259);
     pci_piix4_ide_init(pci_bus, hd, piix4_devfn + 1);
     usb_uhci_piix4_init(pci_bus, piix4_devfn + 2);
-    smbus = piix4_pm_init(pci_bus, piix4_devfn + 3, 0x1100, isa_reserve_irq(9),
+    smbus = piix4_pm_init(pci_bus, piix4_devfn + 3, 0x1100, isa_get_irq(9),
                           NULL, NULL, 0);
     eeprom_buf = qemu_mallocz(8 * 256); /* XXX: make this persistent */
     for (i = 0; i < 8; i++) {
diff --git a/hw/pc_piix.c b/hw/pc_piix.c
index b4ca9ec908..b3ede8941f 100644
--- a/hw/pc_piix.c
+++ b/hw/pc_piix.c
@@ -113,7 +113,7 @@ static void pc_init1(ram_addr_t ram_size,
     }
     isa_bus_irqs(isa_irq);
 
-    pc_register_ferr_irq(isa_reserve_irq(13));
+    pc_register_ferr_irq(isa_get_irq(13));
 
     pc_vga_init(pci_enabled? pci_bus: NULL);
 
@@ -169,7 +169,7 @@ static void pc_init1(ram_addr_t ram_size,
         smi_irq = qemu_allocate_irqs(pc_acpi_smi_interrupt, first_cpu, 1);
         /* TODO: Populate SPD eeprom data.  */
         smbus = piix4_pm_init(pci_bus, piix3_devfn + 3, 0xb100,
-                              isa_reserve_irq(9), *cmos_s3, *smi_irq,
+                              isa_get_irq(9), *cmos_s3, *smi_irq,
                               kvm_enabled());
         for (i = 0; i < 8; i++) {
             DeviceState *eeprom;