3 files changed, 10 insertions, 5 deletions

diff --git a/src/common/common_types.h b/src/common/common_types.h
index 6b1766dca..4cec89fbd 100644
--- a/src/common/common_types.h
+++ b/src/common/common_types.h
@@ -40,10 +40,9 @@ using s64 = std::int64_t; ///< 64-bit signed int
 using f32 = float;  ///< 32-bit floating point
 using f64 = double; ///< 64-bit floating point
 
-// TODO: It would be nice to eventually replace these with strong types that prevent accidental
-// conversion between each other.
-using VAddr = u64; ///< Represents a pointer in the userspace virtual address space.
-using PAddr = u64; ///< Represents a pointer in the ARM11 physical address space.
+using VAddr = u64;    ///< Represents a pointer in the userspace virtual address space.
+using PAddr = u64;    ///< Represents a pointer in the ARM11 physical address space.
+using GPUVAddr = u64; ///< Represents a pointer in the GPU virtual address space.
 
 using u128 = std::array<std::uint64_t, 2>;
 static_assert(sizeof(u128) == 16, "u128 must be 128 bits wide");
diff --git a/src/common/page_table.cpp b/src/common/page_table.cpp
index 8eba1c3f1..69b7abc54 100644
--- a/src/common/page_table.cpp
+++ b/src/common/page_table.cpp
@@ -16,6 +16,7 @@ void PageTable::Resize(std::size_t address_space_width_in_bits) {
 
     pointers.resize(num_page_table_entries);
     attributes.resize(num_page_table_entries);
+    backing_addr.resize(num_page_table_entries);
 
     // The default is a 39-bit address space, which causes an initial 1GB allocation size. If the
     // vector size is subsequently decreased (via resize), the vector might not automatically
@@ -24,6 +25,7 @@ void PageTable::Resize(std::size_t address_space_width_in_bits) {
 
     pointers.shrink_to_fit();
     attributes.shrink_to_fit();
+    backing_addr.shrink_to_fit();
 }
 
 } // namespace Common
diff --git a/src/common/page_table.h b/src/common/page_table.h
index 8339f2890..8b8ff0bb8 100644
--- a/src/common/page_table.h
+++ b/src/common/page_table.h
@@ -21,6 +21,8 @@ enum class PageType : u8 {
     RasterizerCachedMemory,
     /// Page is mapped to a I/O region. Writing and reading to this page is handled by functions.
     Special,
+    /// Page is allocated for use.
+    Allocated,
 };
 
 struct SpecialRegion {
@@ -66,7 +68,7 @@ struct PageTable {
      * Contains MMIO handlers that back memory regions whose entries in the `attribute` vector is
      * of type `Special`.
      */
-    boost::icl::interval_map<VAddr, std::set<SpecialRegion>> special_regions;
+    boost::icl::interval_map<u64, std::set<SpecialRegion>> special_regions;
 
     /**
      * Vector of fine grained page attributes. If it is set to any value other than `Memory`, then
@@ -74,6 +76,8 @@ struct PageTable {
      */
     std::vector<PageType> attributes;
 
+    std::vector<u64> backing_addr;
+
     const std::size_t page_size_in_bits{};
 };