Implement MmpGetPdeAddress() and MmpGetPteAddress() routines for i686 architecture as well as MmpMemoryExtensionEnabled() for checking PAE/LA57 support

xtoskrnl/mm/amd64/init.c

@@ -102,3 +102,18 @@ MmpInitializeArchitecture(VOID)
 {
     UNIMPLEMENTED;
 }
+
+/**
+ * Checks if LA57 (PML5) is enabled.
+ *
+ * @return This routine returns TRUE if LA57 is enabled, or FALSE otherwise.
+ *
+ * @since XT 1.0
+ */
+XTAPI
+BOOLEAN
+MmpMemoryExtensionEnabled(VOID)
+{
+    /* Check if LA57 (PML5) is enabled */
+    return ((ArReadControlRegister(4) & CR4_LA57) != 0) ? TRUE : FALSE;
+}

xtoskrnl/mm/globals.c

@@ -36,5 +36,8 @@ LOADER_MEMORY_MAPPING MmpHalAllocationDescriptors[MM_HAL_ALLOCATION_DESCRIPTORS]
 /* Live address of kernel HAL heap */
 PVOID MmpHalHeapStart = MM_HAL_HEAP_START_ADDRESS;
 
+/* Architecture-specific memory extension */
+BOOLEAN MmpMemoryExtension;
+
 /* Number of used HAL allocation descriptors */
 ULONG MmpUsedHalAllocationDescriptors = 0;

xtoskrnl/mm/i686/init.c

@@ -9,6 +9,67 @@
 #include <xtos.h>
 
 
+/**
+ * Gets the address of the PDE (Page Directory Entry), that maps given address.
+ *
+ * @param Address
+ *        Specifies the address to find the PDE for.
+ *
+ * @return This routine returns the address of the PDE.
+ *
+ * @since XT 1.0
+ */
+XTAPI
+PMMPTE
+MmpGetPdeAddress(PVOID Address)
+{
+    ULONG Offset, PdeBase, PdiShift, PteShift;
+
+    /* Get PDI and PTE shifts based on memory extension flag */
+    if(MmpMemoryExtension)
+    {
+        /* Get bit shifts for PAE system */
+        PdeBase = MM_PDE_PAE_BASE;
+        PdiShift = MM_PDI_PAE_SHIFT;
+        PteShift = MM_PTE_PAE_SHIFT;
+    }
+    else
+    {
+        /* Get bit shifts for non-PAE system */
+        PdeBase = MM_PDE_BASE;
+        PdiShift = MM_PDI_SHIFT;
+        PteShift = MM_PTE_SHIFT;
+    }
+
+    /* Calculate offset and return PTE address */
+    Offset = ((((ULONG)(Address)) >> PdiShift) << PteShift);
+    return (PMMPTE)(PdeBase + Offset);
+}
+
+/**
+ * Gets the address of the PTE (Page Table Entry), that maps given address.
+ *
+ * @param Address
+ *        Specifies the address to find the PTE for.
+ *
+ * @return This routine returns the address of the PTE.
+ *
+ * @since XT 1.0
+ */
+XTAPI
+PMMPTE
+MmpGetPteAddress(PVOID Address)
+{
+    ULONG Offset, PteShift;
+
+    /* Get PTE shift based on memory extension flag */
+    PteShift = MmpMemoryExtension ? MM_PTE_PAE_SHIFT : MM_PTE_SHIFT;
+
+    /* Calculate offset and return PTE address */
+    Offset = ((((ULONG)(Address)) >> MM_PTI_SHIFT) << PteShift);
+    return (PMMPTE)(MM_PTE_BASE + Offset);
+}
+
 /**
  * Performs architecture specific initialization of the XTOS Memory Manager.
  *
@@ -22,3 +83,18 @@ MmpInitializeArchitecture(VOID)
 {
     UNIMPLEMENTED;
 }
+
+/**
+ * Checks if PAE (Physical Address Extension) is enabled.
+ *
+ * @return This routine returns TRUE if PAE is enabled, or FALSE otherwise.
+ *
+ * @since XT 1.0
+ */
+XTAPI
+BOOLEAN
+MmpMemoryExtensionEnabled(VOID)
+{
+    /* Check if PAE is enabled */
+    return ((ArReadControlRegister(4) & CR4_PAE) != 0) ? TRUE : FALSE;
+}

xtoskrnl/mm/init.c

@@ -9,6 +9,21 @@
 #include <xtos.h>
 
 
+/**
+ * Performs an early pre-initialization of hardware-related structures.
+ *
+ * @return This routine does not return any value.
+ *
+ * @since XT 1.0
+ */
+XTAPI
+VOID
+MmInitializeHardware(VOID)
+{
+    /* Check for architecture-specific memory extensions enabled by the firmware or boot loader */
+    MmpMemoryExtension = MmpMemoryExtensionEnabled();
+}
+
 /**
  * Performs an early initialization of the XTOS Memory Manager.
  *