Add suspend_interrupts() and resume_interrupts()

src/hulk/cpu.d

@@ -135,6 +135,37 @@ enum uint CPUID_1_ECX_RDRND = 0x4000_0000u;
 enum uint CPUID_1_ECX_HYPERVISOR = 0x8000_0000u;
 /** @} */
 
+/** Interrupt suspend level (0 when interrupts are enabled). */
+private __gshared size_t intr_suspend_level;
+
+/**
+ * Suspend interrupts.
+ *
+ * This function disables interrupts. Calls can be nested and interrupts will
+ * be enabled only when the outermost pair of
+ * suspend_interrupts()/resume_interrupts() is complete.
+ */
+void suspend_interrupts()
+{
+    cli();
+    intr_suspend_level++;
+}
+
+/**
+ * Resume interrupts.
+ *
+ * Calls can be nested and interrupts will be enabled only when the outermost
+ * pair of suspend_interrupts()/resume_interrupts() is complete.
+ */
+void resume_interrupts()
+{
+    intr_suspend_level--;
+    if (intr_suspend_level == 0)
+    {
+        sti();
+    }
+}
+
 void cli()
 {
     __asm("cli", "");

src/hulk/hulk.d

@@ -58,7 +58,8 @@ private void initialize_cpu()
  */
 void hulk_start()
 {
-    cli();
+    suspend_interrupts();
+
     initialize_cpu();
     Serial.initialize();
     Gdt.initialize();
@@ -86,7 +87,8 @@ void hulk_start()
     Pit.initialize();
     Pci.initialize();
     Usb.initialize();
-    sti();
+
+    resume_interrupts();
 
     /* Check that PIT millisecond interrupt is firing. */
     size_t uptime = Time.uptime();