diff --git a/lagarto-ox.nix b/lagarto-ox.nix
index 9dbc792..b34eb4c 100644
--- a/lagarto-ox.nix
+++ b/lagarto-ox.nix
@@ -173,16 +173,88 @@
 
           set -x
 
-          ip addr
-          cat /proc/interrupts
+          (
+            echo "--- Testing threshold register init value"
+            # Ensure that reading a few times the threshold value
+            # always gives the same initial value 0
+            t1=$(devmem 0x40a00000) # Read context 1 threshold value
+            t2=$(devmem 0x40a00000) # Read context 1 threshold value
+            t3=$(devmem 0x40a00000) # Read context 1 threshold value
+            found="$t1 $t2 $t3"
+            expected="0x00000000 0x00000000 0x00000000"
+            if [ "$found" = "$expected" ]; then
+              echo "--- Threshold init value: OK"
+            else
+              echo "found   =$found"
+              echo "expected=$expected"
+              echo "--- Threshold init value: FAIL"
+            fi
+          )
 
-          modprobe xxvnet_carv
+          (
+            echo "--- Testing threshold register stability"
+            # Write the priority register of an interrupt and ensure
+            # the threshold register didn't change
+            devmem 0x40a00000 32 0 # Write context 1 threshold value 0
+            t1=$(devmem 0x40a00000) # Read context 1 threshold value
+            devmem 0x40800010 32 5 # Write source 4 priority value 5
+            t2=$(devmem 0x40a00000) # Read context 1 threshold value
+            found="$t1 $t2"
+            expected="0x00000000 0x00000000"
+            if [ "$found" = "$expected" ]; then
+              echo "--- Threshold stability: OK"
+            else
+              echo "found   =$found"
+              echo "expected=$expected"
+              echo "--- Threshold stability: FAIL"
+            fi
+          )
 
-          plictool -c2
-          plictool -c2
-          plictool -c2
+          (
+            echo "--- Testing claim register"
 
-          ip addr
+            # Use aux timer on source 4 for this one
+            pending=$(devmem 0x40801000) # Dump pending bits of sources 0-31
+
+            # Ensure the aux timer is pending
+            if [ "$pending" = "0x00000018" ]; then
+
+              # Make sure the priority is higher than the threshold
+              devmem 0x40800010 32 0x10 # Write source 4 priority value 16
+              devmem 0x40802080 32 0x10 # Enable source 4 in context 1
+              # Writing the threshold has to be last, otherwise it will change
+              devmem 0x40a00000 32 0    # Write context 1 threshold value 0
+              c1=$(devmem 0x40a01004)   # Claim context 1
+              c2=$(devmem 0x40a01004)   # Claim context 1
+              c3=$(devmem 0x40a01004)   # Claim context 1
+              found="$c1 $c2 $c3"
+              expected="0x00000004 0x00000004 0x00000004"
+              if [ "$found" = "$expected" ]; then
+                echo "--- Testing claim register: OK"
+              else
+                echo "found   =$found"
+                echo "expected=$expected"
+                echo "--- Testing claim register: FAIL"
+              fi
+            else
+              echo "unknown pending bits: $pending"
+              echo "--- Testing claim register: SKIP"
+            fi
+          )
+
+          echo "all done, waiting forever..."
+          while [ 1 ]; do sleep 9999; done
+
+          # ip addr
+          # cat /proc/interrupts
+
+          # modprobe xxvnet_carv
+
+          # plictool -c2
+          # plictool -c2
+          # plictool -c2
+
+          # ip addr
 
           exec /init
         '';