[NTOS:CM] Implement Win7+ VolatileBoot support.

Its support is controlled with a REG_DWORD value named
`VolatileBoot` inside the registry key
`HKLM\SYSTEM\CurrentControlSet\Control\Session Manager\Configuration Manager` .

Its implementation is very trivial: when enabled, CmpShareSystemHives
is set to TRUE and doesn't change state during runtime.
In a sense this is similar to what happens in WinPE-boot, except that
ALL hives without exception (system hives and others) will be loaded
in shared mode.

ntoskrnl/config/cmdata.c

···
 
 UNICODE_STRING CmpLoadOptions;
 
+/* TRUE if all hives must be loaded in shared mode */
+ULONG CmpVolatileBoot;
 /* TRUE if the system hives must be loaded in shared mode */
 BOOLEAN CmpShareSystemHives;
 /* TRUE when the registry is in PE mode */
···
         L"Session Manager\\Configuration Manager",
         L"SelfHealingEnabled",
         &CmSelfHeal,
+        NULL,
+        NULL
+    },
+    {
+        L"Session Manager\\Configuration Manager",
+        L"VolatileBoot",
+        &CmpVolatileBoot,
         NULL,
         NULL
     },

ntoskrnl/config/cmsysini.c

···
         return FALSE;
     }
 
-    /* Completely sucessful */
+    /* Completely successful */
     return TRUE;
 }
 
···
         CmpMiniNTBoot = TRUE;
         CmpShareSystemHives = TRUE;
     }
+    /* If we are in volatile boot mode, ALL hives without exception
+     * (system hives and others) will be loaded in shared mode */
+    if (CmpVolatileBoot)
+        CmpShareSystemHives = TRUE;
 
     /* Initialize the hive list and lock */
     InitializeListHead(&CmpHiveListHead);

ntoskrnl/include/internal/cm.h

···
 extern ULONG CmpTraceLevel;
 extern BOOLEAN CmpSpecialBootCondition;
 extern BOOLEAN CmpFlushOnLockRelease;
+extern ULONG CmpVolatileBoot;
 extern BOOLEAN CmpShareSystemHives;
 extern BOOLEAN CmpMiniNTBoot;
 extern BOOLEAN CmpNoVolatileCreates;