fix: boottimer device MMIO address

resources/overlay/usr/local/bin/init.c

@@ -13,7 +13,7 @@
 // Position on the bus is defined by MMIO_LEN increments, where MMIO_LEN is
 // defined as 0x1000 in vmm/src/device_manager/mmio.rs.
 #ifdef __x86_64__
-#define MAGIC_MMIO_SIGNAL_GUEST_BOOT_COMPLETE 0xd0000000
+#define MAGIC_MMIO_SIGNAL_GUEST_BOOT_COMPLETE 0xc0000000
 #endif
 #ifdef __aarch64__
 #define MAGIC_MMIO_SIGNAL_GUEST_BOOT_COMPLETE 0x40000000

resources/rebuild.sh

@@ -92,7 +92,7 @@ function build_initramfs {
 
     # Report guest boot time back to Firecracker via MMIO
     # See arch/src/lib.rs and the BootTimer device
-    MAGIC_BOOT_ADDRESS=0xd0000000
+    MAGIC_BOOT_ADDRESS=0xc0000000
     if [ $ARCH = "aarch64" ]; then
         MAGIC_BOOT_ADDRESS=0x40000000
     fi

tests/integration_tests/performance/test_boottime.py

@@ -94,6 +94,33 @@ def to_ms(v, unit):
     return kernel, userspace, total
 
 
+def launch_vm_with_boot_timer(
+    microvm_factory, guest_kernel_acpi, rootfs_rw, vcpu_count, mem_size_mib
+):
+    """Launches a microVM with guest-timer and returns the reported metrics for it"""
+    vm = microvm_factory.build(guest_kernel_acpi, rootfs_rw)
+    vm.jailer.extra_args.update({"boot-timer": None})
+    vm.spawn()
+    vm.basic_config(
+        vcpu_count=vcpu_count,
+        mem_size_mib=mem_size_mib,
+        boot_args=DEFAULT_BOOT_ARGS + " init=/usr/local/bin/init",
+        enable_entropy_device=True,
+    )
+    vm.add_net_iface()
+    vm.start()
+    vm.pin_threads(0)
+
+    boot_time_us, cpu_boot_time_us = get_boottime_device_info(vm)
+
+    return (vm, boot_time_us, cpu_boot_time_us)
+
+
+def test_boot_timer(microvm_factory, guest_kernel_acpi, rootfs):
+    """Tests that the boot timer device works"""
+    launch_vm_with_boot_timer(microvm_factory, guest_kernel_acpi, rootfs, 1, 128)
+
+
 @pytest.mark.parametrize(
     "vcpu_count,mem_size_mib",
     [(1, 128), (1, 1024), (2, 2048), (4, 4096)],
@@ -105,20 +132,9 @@ def test_boottime(
     """Test boot time with different guest configurations"""
 
     for i in range(10):
-        vm = microvm_factory.build(guest_kernel_acpi, rootfs_rw)
-        vm.jailer.extra_args.update({"boot-timer": None})
-        vm.spawn()
-        vm.basic_config(
-            vcpu_count=vcpu_count,
-            mem_size_mib=mem_size_mib,
-            boot_args=DEFAULT_BOOT_ARGS + " init=/usr/local/bin/init",
-            enable_entropy_device=True,
+        vm, boot_time_us, cpu_boot_time_us = launch_vm_with_boot_timer(
+            microvm_factory, guest_kernel_acpi, rootfs_rw, vcpu_count, mem_size_mib
         )
-        vm.add_net_iface()
-        vm.start()
-        vm.pin_threads(0)
-
-        boot_time_us, cpu_boot_time_us = get_boottime_device_info(vm)
 
         if i == 0:
             metrics.set_dimensions(