diff --git a/src/hulk/usb/xhci.d b/src/hulk/usb/xhci.d
index de54d42..013ab35 100644
--- a/src/hulk/usb/xhci.d
+++ b/src/hulk/usb/xhci.d
@@ -118,6 +118,11 @@ struct XHCI
          * 31:12 VTIO register space offset (xHCI v1.2+)
          */
         Volatile!uint vtios_offset;
+
+        @property ubyte max_slots()
+        {
+            return this.hcs_params1 & 0xFFu;
+        }
     }
     static assert(CapabilityRegisters.sizeof == 0x24u);
 
@@ -364,9 +369,7 @@ struct XHCI
         /* Allocate memory for various controller data structures. */
         ubyte * page = cast(ubyte *)Hippo.allocate_page();
         /* Device Context Index: 2K */
-        void * device_context_index = page;
-        /* Device Context: 2K */
-        void * device_context = &page[2048];
+        void ** device_context_index = cast(void **)page;
         page = cast(ubyte *)Hippo.allocate_page();
         /* Input Control Context: 64 bytes */
         void * input_control_context = page;
@@ -377,7 +380,7 @@ struct XHCI
         /* Stream Context: 16 bytes */
         void * stream_context = &page[192];
         /* Scratchpad Buffer Array: 248 bytes */
-        void * scratchpad_buffer_array = &page[256];
+        void ** scratchpad_buffer_array = cast(void **)&page[256];
         /* Stream Array (Linear): 1M */
         void * stream_array_linear = Hippo.allocate_aligned_region(1024 * 1024, PAGE_SIZE);
         /* Stream Array (Pri/Sec): 4K */
@@ -393,6 +396,24 @@ struct XHCI
         /* Scratchpad Buffers: 4K */
         void * scratchpad_buffers = Hippo.allocate_page();
 
+        device_context_index[0] = scratchpad_buffer_array;
+
+        size_t max_slots = m_capability_registers.max_slots;
+        for (size_t i = 0u; i < max_slots; i++)
+        {
+            void * addr;
+            if ((i & 1) == 0)
+            {
+                page = cast(ubyte *)Hippo.allocate_page();
+                addr = page;
+            }
+            else
+            {
+                addr = &page[2048];
+            }
+            device_context_index[1 + i] = addr;
+        }
+
         /* TODO: write dcbaap. */
         /* TODO: write cr_ctrl. */
         /+ TODO: