OcAppleBootCompatLib: Added free memory debugging

Include/Library/OcMemoryLib.h

@@ -200,6 +200,18 @@ CountRuntimePages (
   OUT UINTN                  *DescriptorCount OPTIONAL
   );
 
+/**
+  Calculate number of free pages in the memory map.
+
+  @param[out]    LowerMemory    Number of free pages below 4 GB, optional.
+
+  @retval Number of free pages.
+**/
+UINTN
+CountFreePages (
+  OUT UINTN                  *LowerMemory  OPTIONAL
+  );
+
 /**
   Return pointer to PML4 table in PageTable and PWT and PCD flags in Flags.
 

Library/OcAppleBootCompatLib/OcAppleBootCompatLib.c

@@ -101,12 +101,24 @@ OcAbcInitialize (
 {
   EFI_STATUS           Status;
   BOOT_COMPAT_CONTEXT  *BootCompat;
+  UINTN                LowMemory;
+  UINTN                TotalMemory;
 
   Status = InstallAbcProtocol ();
   if (EFI_ERROR (Status)) {
     return Status;
   }
 
+  DEBUG_CODE_BEGIN ();
+  TotalMemory = CountFreePages (&LowMemory);
+  DEBUG ((
+    DEBUG_INFO,
+    "OCABC: Firmware has %Lu free pages (%Lu in lower 4 GB)\n",
+    (UINT64) TotalMemory,
+    (UINT64) LowMemory
+    ));
+  DEBUG_CODE_END ();
+
   BootCompat = GetBootCompatContext ();
 
   CopyMem (

Library/OcMemoryLib/MemoryMap.c

@@ -380,3 +380,51 @@ CountRuntimePages (
 
   return PageNum;
 }
+
+UINTN
+CountFreePages (
+  OUT UINTN                  *LowerMemory  OPTIONAL
+  )
+{
+  UINTN                        MemoryMapSize;
+  UINTN                        DescriptorSize;
+  EFI_MEMORY_DESCRIPTOR        *MemoryMap;
+  EFI_MEMORY_DESCRIPTOR        *EntryWalker;
+  UINTN                        FreePages;
+
+  FreePages = 0;
+  if (LowerMemory != NULL) {
+    *LowerMemory = 0;
+  }
+
+  MemoryMap = GetCurrentMemoryMap (&MemoryMapSize, &DescriptorSize, NULL, NULL);
+  if (MemoryMap == NULL) {
+    return 0;
+  }
+
+  for (
+    EntryWalker = MemoryMap;
+    (UINT8 *) EntryWalker < ((UINT8 *) MemoryMap + MemoryMapSize);
+    EntryWalker = NEXT_MEMORY_DESCRIPTOR (EntryWalker, DescriptorSize)) {
+
+    if (EntryWalker->Type != EfiConventionalMemory) {
+      continue;
+    }
+
+    FreePages += EntryWalker->NumberOfPages;
+
+    if (LowerMemory == NULL || EntryWalker->PhysicalStart >= BASE_4GB) {
+      continue;
+    }
+
+    if (EntryWalker->PhysicalStart + EFI_PAGES_TO_SIZE (EntryWalker->NumberOfPages) > BASE_4GB) {
+      *LowerMemory += EFI_SIZE_TO_PAGES (BASE_4GB - EntryWalker->PhysicalStart);
+    } else {
+      *LowerMemory += EntryWalker->NumberOfPages;
+    }
+  }
+
+  FreePool (MemoryMap);
+
+  return FreePages;
+}