Initial memory manager initialization code

xtoskrnl/mm/init.c

@@ -0,0 +1,147 @@
+/**
+ * PROJECT:         ExectOS
+ * COPYRIGHT:       See COPYING.md in the top level directory
+ * FILE:            xtoskrnl/mm/init.c
+ * DESCRIPTION:     Memory Manager initialization routines
+ * DEVELOPERS:      Rafal Kupiec <belliash@codingworkshop.eu.org>
+ */
+
+#include <xtos.h>
+
+
+/**
+ * Performs an early initialization of the XTOS Memory Manager.
+ *
+ * @return This routine does not return any value.
+ *
+ * @since XT 1.0
+ */
+XTAPI
+VOID
+MmInitializeMemoryManager()
+{
+    /* Scan memory descriptors provided by the boot loader */
+    MmpScanMemoryDescriptors();
+
+    /* Check if there are enough physical pages */
+    if(MmNumberOfPhysicalPages < MM_MINIMUM_PHYSICAL_PAGES)
+    {
+        /* Insufficient physical pages, kernel panic */
+        DebugPrint(L"Insufficient physical pages! Install additional memory\n");
+        KePanic(0);
+    }
+
+    /* Proceed with architecture specific initialization */
+    MmpInitializeArchitecture();
+}
+
+/**
+ * Scans memory descriptors provided by the boot loader.
+ *
+ * @return This routine does not return any value.
+ *
+ * @since XT 1.0
+ */
+XTAPI
+VOID
+MmpScanMemoryDescriptors()
+{
+    PLOADER_MEMORY_MAPPING MemoryDescriptor;
+    PLIST_ENTRY MemoryMappings;
+    PFN_NUMBER FreePages;
+
+    /* Initially, set number of free pages to 0 */
+    FreePages = 0;
+
+    /* Iterate through memory mappings provided by the boot loader */
+    MemoryMappings = KeInitializationBlock->MemoryDescriptorListHead.Flink;
+    while(MemoryMappings != &KeInitializationBlock->MemoryDescriptorListHead)
+    {
+        /* Get memory descriptor */
+        MemoryDescriptor = CONTAIN_RECORD(MemoryMappings, LOADER_MEMORY_MAPPING, ListEntry);
+
+        /* Check if memory type is invisible or cached */
+        if(MmpVerifyMemoryTypeInvisible(MemoryDescriptor->MemoryType) ||
+           (MemoryDescriptor->MemoryType == LoaderHALCachedMemory))
+        {
+            /* Skip this mapping */
+            MemoryMappings = MemoryMappings->Flink;
+            continue;
+        }
+
+        /* Make sure that memory type is not bad */
+        if(MemoryDescriptor->MemoryType != LoaderBad)
+        {
+            /* Increment number of physical pages */
+            MmNumberOfPhysicalPages += MemoryDescriptor->PageCount;
+        }
+
+        /* Find lowest physical page */
+        if(MemoryDescriptor->BasePage < MmLowestPhysicalPage)
+        {
+            /* Update lowest physical page */
+            MmLowestPhysicalPage = MemoryDescriptor->BasePage;
+        }
+
+        /* Find highest physical page */
+        if(MemoryDescriptor->BasePage + MemoryDescriptor->PageCount > MmHighestPhysicalPage)
+        {
+            /* Update highest physical page */
+            MmHighestPhysicalPage = (MemoryDescriptor->BasePage + MemoryDescriptor->PageCount) - 1;
+        }
+
+        /* Check if memory type should be considered as free */
+        if(MmpVerifyMemoryTypeFree(MemoryDescriptor->MemoryType))
+        {
+            /* Check if this descriptor contains more free pages */
+            if(MemoryDescriptor->PageCount >= FreePages)
+            {
+                /* Update free descriptor */
+                FreePages = MemoryDescriptor->PageCount;
+                MmFreeDescriptor = MemoryDescriptor;
+            }
+        }
+
+        /* Get next memory descriptor */
+        MemoryMappings = MemoryMappings->Flink;
+    }
+
+    /* Store original free descriptor */
+    MmOldFreeDescriptor = *MmFreeDescriptor;
+}
+
+/** Checks whether the specified memory type should be considered as free.
+ *
+ * @param MemoryType
+ *        Specifies the memory type to verify.
+ *
+ * @return This routine returns TRUE if the specified memory type should be considered as free, or FALSE otherwise.
+ *
+ * @since XT 1.0
+ */
+XTAPI
+BOOLEAN
+MmpVerifyMemoryTypeFree(LOADER_MEMORY_TYPE MemoryType)
+{
+    return (MemoryType == LoaderFree) || (MemoryType == LoaderFirmwareTemporary) ||
+           (MemoryType == LoaderLoadedProgram) || (MemoryType == LoaderOsloaderStack);
+}
+
+/**
+ * Checks whether the specified memory type should be considered as invisible for the memory manager.
+ *
+ * @param MemoryType
+ *        Specifies the memory type to verify.
+ *
+ * @return This routine returns TRUE if the specified memory type should be considered as invisible, or FALSE otherwise.
+ *
+ * @since XT 1.0
+ */
+XTAPI
+BOOLEAN
+MmpVerifyMemoryTypeInvisible(LOADER_MEMORY_TYPE MemoryType)
+{
+    return (MemoryType == LoaderFirmwarePermanent) ||
+           (MemoryType == LoaderSpecialMemory) ||
+           (MemoryType == LoaderBBTMemory);
+}