MdeModulePkg: UefiBootManagerLib: Change default alignment for ramdis…

…k boot

The ramdisk is modelled as an NVDIMM which have a naturally higher
alignment than 4K. Operating systems may wish to map NVDIMMs using large
pages, so force the allocation alignment to 2MB.

This change was tested using HTTP ramdisk boot, targeting a flat windows
image.

Signed-off-by: Kun Qin <[email protected]>

MdeModulePkg/Library/UefiBootManagerLib/BmBoot.c

@@ -1398,7 +1398,8 @@ BmDestroyRamDisk (
 
   Status = mRamDisk->Unregister (RamDiskDevicePath);
   ASSERT_EFI_ERROR (Status);
-  FreePages (RamDiskBuffer, RamDiskSizeInPages);
+  // MU_CHANGE - Ramdisk is now allocated with alignment.
+  FreeAlignedPages (RamDiskBuffer, RamDiskSizeInPages);
 }
 
 /**
@@ -1446,10 +1447,17 @@ BmExpandLoadFile (
     return DuplicateDevicePath (DevicePathFromHandle (LoadFileHandle));
   }
 
+  // MU_CHANGE [BEGIN] - Ramdisk is now allocated with 2MB alignment.
+
   //
   // The load option resides in a RAM disk.
+  // Use a reasonable default of 2MB for alignment as the ramdisk device is
+  // implemented as an NVDIMM persistent memory and operating systems may
+  // wish to map this with huge page support.
   //
-  FileBuffer = AllocateReservedPages (EFI_SIZE_TO_PAGES (BufferSize));
+
+  FileBuffer = AllocateAlignedReservedPages (EFI_SIZE_TO_PAGES (BufferSize), SIZE_2MB);
+  // MU_CHANGE [END] - Ramdisk is now allocated with 2MB alignment.
   if (FileBuffer == NULL) {
     DEBUG_CODE_BEGIN ();
     EFI_DEVICE_PATH  *LoadFilePath;
@@ -1490,7 +1498,8 @@ BmExpandLoadFile (
 
   Status = LoadFile->LoadFile (LoadFile, FilePath, TRUE, &BufferSize, FileBuffer);
   if (EFI_ERROR (Status)) {
-    FreePages (FileBuffer, EFI_SIZE_TO_PAGES (BufferSize));
+    // MU_CHANGE - Ramdisk is now allocated with alignment.
+    FreeAlignedPages (FileBuffer, EFI_SIZE_TO_PAGES (BufferSize));
     return NULL;
   }