Add lesson 17

22 files changed, 855 insertions, 0 deletions

diff --git a/Lesson_17/BootManager.png b/Lesson_17/BootManager.png
new file mode 100644
index 0000000..715b357
--- /dev/null
+++ b/Lesson_17/BootManager.png
diff --git a/Lesson_17/Conf/target.txt b/Lesson_17/Conf/target.txt
new file mode 100644
index 0000000..c109dcf
--- /dev/null
+++ b/Lesson_17/Conf/target.txt
@@ -0,0 +1,7 @@
+ACTIVE_PLATFORM       = UefiLessonsPkg/UefiLessonsPkg.dsc

+TARGET                = RELEASE

+TARGET_ARCH           = X64

+TOOL_CHAIN_CONF       = Conf/tools_def.txt

+TOOL_CHAIN_TAG        = GCC5

+BUILD_RULE_CONF = Conf/build_rule.txt

+

diff --git a/Lesson_17/README.md b/Lesson_17/README.md
new file mode 100644
index 0000000..6dd3ed6
--- /dev/null
+++ b/Lesson_17/README.md
@@ -0,0 +1,91 @@
+In the last lesson we've added our own boot option.
+
+Let's boot it.
+
+Type `exit` in the UEFI shell to go to the BIOS menu:
+```
+Shell> exit
+```
+Navigate to the `Boot Manager` window. Our `HelloWorld` option would be present here:
+![Boot Manager](BootManager.png?raw=true "Boot manager")
+
+If you'll try to boot it, app would print its strings and immediately return.
+
+Let's fix it. Let's add wait for a key input from user in our app code.
+To do it we will need `WaitForEvent` blocking function:
+
+```
+EFI_BOOT_SERVICES.WaitForEvent()
+
+Summary
+Stops execution until an event is signaled.
+
+Prototype
+typedef
+
+EFI_STATUS
+(EFIAPI *EFI_WAIT_FOR_EVENT) (
+ IN UINTN NumberOfEvents,
+ IN EFI_EVENT *Event,
+ OUT UINTN *Index
+);
+
+Parameters
+NumberOfEvents 	The number of events in the Event array.
+Event 		An array of EFI_EVENT.
+Index 		Pointer to the index of the event which satisfied the wait condition.
+```
+
+To our task we should use `EFI_EVENT WaitForKey` from the `EFI_SIMPLE_TEXT_INPUT_PROTOCOL` (which is placed in a `gST->ConIn`)
+```
+typedef struct _EFI_SIMPLE_TEXT_INPUT_PROTOCOL {
+ EFI_INPUT_RESET Reset;
+ EFI_INPUT_READ_KEY ReadKeyStroke;
+ EFI_EVENT WaitForKey;
+} EFI_SIMPLE_TEXT_INPUT_PROTOCOL;
+```
+
+Now when we now all this API add this code to the end of the `HelloWorld` app main function:
+```
+UINTN Index;
+gBS->WaitForEvent(1, &(gST->ConIn->WaitForKey), &Index);
+```
+
+Compile OVMF again and try to boot our `HelloWorld` boot option through the `Boot Manager` BIOS menu.
+Now output of the app stops and waits for the user keystroke.
+
+Everything works fine except a fact that if we choose `Enter` as our keystroke, `HelloWorld` app would be immediately launched again.
+
+This happens because we didn't read or clear the input buffer. As we don't need keystroke information let's simply reset it with a `Reset` function:
+```
+EFI_SIMPLE_TEXT_INPUT_PROTOCOL.Reset()
+
+Summary:
+Resets the input device hardware.
+
+Prototype:
+typedef
+EFI_STATUS
+(EFIAPI *EFI_INPUT_RESET) (
+ IN EFI_SIMPLE_TEXT_INPUT_PROTOCOL *This,
+ IN BOOLEAN ExtendedVerification
+ );
+
+Parameters:
+This 			A pointer to the EFI_SIMPLE_TEXT_INPUT_PROTOCOL instance.
+ExtendedVerification	Indicates that the driver may perform a more exhaustive verification
+			operation of the device during reset.
+
+Description:
+The Reset() function resets the input device hardware.
+The implementation of Reset is required to clear the contents of any input queues resident in memory
+used for buffering keystroke data and put the input stream in a known empty state
+```
+
+Add this to the end of our app:
+```
+gST->ConIn->Reset(gST->ConIn, FALSE);
+```
+
+Now if we boot our app from the `Boot Manager` BIOS menu it would work correctly for any keystroke.
+
diff --git a/Lesson_17/UefiLessonsPkg/HelloWorld/HelloWorld.c b/Lesson_17/UefiLessonsPkg/HelloWorld/HelloWorld.c
new file mode 100644
index 0000000..29a4812
--- /dev/null
+++ b/Lesson_17/UefiLessonsPkg/HelloWorld/HelloWorld.c
@@ -0,0 +1,19 @@
+#include <Library/UefiBootServicesTableLib.h>
+#include <Library/UefiLib.h>
+
+EFI_STATUS
+EFIAPI
+UefiMain (
+  IN EFI_HANDLE        ImageHandle,
+  IN EFI_SYSTEM_TABLE  *SystemTable
+  )
+{
+  SystemTable->ConOut->OutputString(SystemTable->ConOut, L"Hello World!\n");
+  gST->ConOut->OutputString(gST->ConOut, L"Hello again!\n");
+  Print(L"Bye!\n");
+
+  UINTN Index;
+  gBS->WaitForEvent(1, &(gST->ConIn->WaitForKey), &Index);
+  gST->ConIn->Reset(gST->ConIn, FALSE);
+  return EFI_SUCCESS;
+}
diff --git a/Lesson_17/UefiLessonsPkg/HelloWorld/HelloWorld.inf b/Lesson_17/UefiLessonsPkg/HelloWorld/HelloWorld.inf
new file mode 100644
index 0000000..d65ca2e
--- /dev/null
+++ b/Lesson_17/UefiLessonsPkg/HelloWorld/HelloWorld.inf
@@ -0,0 +1,18 @@
+[Defines]
+  INF_VERSION                    = 1.25
+  BASE_NAME                      = HelloWorld
+  FILE_GUID                      = 2e55fa38-f148-42d3-af90-1be247323e30
+  MODULE_TYPE                    = UEFI_APPLICATION
+  VERSION_STRING                 = 1.0
+  ENTRY_POINT                    = UefiMain
+
+[Sources]
+  HelloWorld.c
+
+[Packages]
+  MdePkg/MdePkg.dec
+
+[LibraryClasses]
+  UefiApplicationEntryPoint
+  UefiLib
+
diff --git a/Lesson_17/UefiLessonsPkg/ImageHandle/ImageHandle.c b/Lesson_17/UefiLessonsPkg/ImageHandle/ImageHandle.c
new file mode 100644
index 0000000..32e9c43
--- /dev/null
+++ b/Lesson_17/UefiLessonsPkg/ImageHandle/ImageHandle.c
@@ -0,0 +1,105 @@
+#include <Library/MemoryAllocationLib.h>
+#include <Library/UefiBootServicesTableLib.h>
+#include <Library/UefiLib.h>
+
+typedef struct {
+  UINTN               Signature;
+  /// All handles list of IHANDLE
+  LIST_ENTRY          AllHandles;
+  /// List of PROTOCOL_INTERFACE's for this handle
+  LIST_ENTRY          Protocols;
+  UINTN               LocateRequest;
+  /// The Handle Database Key value when this handle was last created or modified
+  UINT64              Key;
+} IHANDLE;
+
+typedef struct {
+  UINTN               Signature;
+  /// Link Entry inserted to mProtocolDatabase
+  LIST_ENTRY          AllEntries;
+  /// ID of the protocol
+  EFI_GUID            ProtocolID;
+  /// All protocol interfaces
+  LIST_ENTRY          Protocols;
+  /// Registerd notification handlers
+  LIST_ENTRY          Notify;
+} PROTOCOL_ENTRY;
+
+typedef struct {
+  UINTN                       Signature;
+  /// Link on IHANDLE.Protocols
+  LIST_ENTRY                  Link;
+  /// Back pointer
+  IHANDLE                     *Handle;
+  /// Link on PROTOCOL_ENTRY.Protocols
+  LIST_ENTRY                  ByProtocol;
+  /// The protocol ID
+  PROTOCOL_ENTRY              *Protocol;
+  /// The interface value
+  VOID                        *Interface;
+  /// OPEN_PROTOCOL_DATA list
+  LIST_ENTRY                  OpenList;
+  UINTN                       OpenListCount;
+
+} PROTOCOL_INTERFACE;
+
+
+#define offsetof(a,b) ((INTN)(&(((a*)(0))->b)))
+
+#define container_of(ptr, type, member) ({                      \
+        const typeof( ((type *)0)->member ) *__mptr = (ptr);    \
+        (type *)( (char *)__mptr - offsetof(type,member) );})
+
+EFI_STATUS
+EFIAPI
+UefiMain (
+  IN EFI_HANDLE        ImageHandle,
+  IN EFI_SYSTEM_TABLE  *SystemTable
+  )
+{
+  IHANDLE* MyHandle = ImageHandle;
+  Print(L"Signature: %c %c %c %c\n", (MyHandle->Signature >>  0) & 0xff,
+                                     (MyHandle->Signature >>  8) & 0xff,
+                                     (MyHandle->Signature >> 16) & 0xff,
+                                     (MyHandle->Signature >> 24) & 0xff);
+
+  Print(L"Back Protocol Interface Link: %p\n", MyHandle->Protocols.BackLink);
+  Print(L"Forward Protocol Interface Link: %p\n", MyHandle->Protocols.ForwardLink);
+
+  LIST_ENTRY *FirstLink = MyHandle->Protocols.ForwardLink;
+  LIST_ENTRY *CurrentLink = FirstLink;
+  do {
+  	PROTOCOL_INTERFACE* MyProtocolInterface = container_of(CurrentLink, PROTOCOL_INTERFACE, Link);
+
+        Print(L"\n");
+        Print(L"Current Link: %p\n", CurrentLink);
+  	Print(L"Signature: %x %x %x %x\n", (MyProtocolInterface->Signature >>  0) & 0xff,
+        	                           (MyProtocolInterface->Signature >>  8) & 0xff,
+                	                   (MyProtocolInterface->Signature >> 16) & 0xff,
+                        	           (MyProtocolInterface->Signature >> 24) & 0xff);
+
+  	Print(L"Back Link: %p\n", MyProtocolInterface->Link.BackLink);
+	Print(L"Forward Link: %p\n", MyProtocolInterface->Link.ForwardLink);
+	Print(L"GUID=%g\n", MyProtocolInterface->Protocol->ProtocolID);
+        CurrentLink = MyProtocolInterface->Link.ForwardLink;
+  } while (CurrentLink != FirstLink);
+
+  Print(L"________\n");
+  EFI_GUID **ProtocolGuidArray;
+  UINTN ArrayCount;
+  //EFI_STATUS Status = gBS->ProtocolsPerHandle(NULL,		// Use this to test %r Print formatting option
+  EFI_STATUS Status = gBS->ProtocolsPerHandle(ImageHandle,
+					      &ProtocolGuidArray,
+					      &ArrayCount);
+
+  if (!EFI_ERROR(Status)) {
+    for (int i=0; i<ArrayCount; i++) {
+      Print(L"%g\n", ProtocolGuidArray[i]);
+    }
+    FreePool(ProtocolGuidArray);
+  } else {
+    Print(L"ProtocolsPerHandle error: %r\n", Status);
+  }
+
+  return EFI_SUCCESS;
+}
diff --git a/Lesson_17/UefiLessonsPkg/ImageHandle/ImageHandle.inf b/Lesson_17/UefiLessonsPkg/ImageHandle/ImageHandle.inf
new file mode 100644
index 0000000..34256ee
--- /dev/null
+++ b/Lesson_17/UefiLessonsPkg/ImageHandle/ImageHandle.inf
@@ -0,0 +1,18 @@
+[Defines]
+  INF_VERSION                    = 1.25
+  BASE_NAME                      = ImageHandle
+  FILE_GUID                      = b68d3472-70c7-4928-841b-6566032e0a23
+  MODULE_TYPE                    = UEFI_APPLICATION
+  VERSION_STRING                 = 1.0
+  ENTRY_POINT                    = UefiMain
+
+[Sources]
+  ImageHandle.c
+
+[Packages]
+  MdePkg/MdePkg.dec
+
+[LibraryClasses]
+  UefiApplicationEntryPoint
+  UefiLib
+
diff --git a/Lesson_17/UefiLessonsPkg/ImageInfo/ImageInfo.c b/Lesson_17/UefiLessonsPkg/ImageInfo/ImageInfo.c
new file mode 100644
index 0000000..c45570e
--- /dev/null
+++ b/Lesson_17/UefiLessonsPkg/ImageInfo/ImageInfo.c
@@ -0,0 +1,44 @@
+#include <Library/UefiBootServicesTableLib.h>
+#include <Library/UefiLib.h>
+
+#include <Protocol/LoadedImage.h>
+#include <Library/DevicePathLib.h>
+
+EFI_STATUS
+EFIAPI
+UefiMain (
+  IN EFI_HANDLE        ImageHandle,
+  IN EFI_SYSTEM_TABLE  *SystemTable
+  )
+{
+  EFI_STATUS Status;
+  EFI_LOADED_IMAGE_PROTOCOL* LoadedImage;
+
+  Status = gBS->HandleProtocol(
+    ImageHandle,
+    &gEfiLoadedImageProtocolGuid,
+    (VOID **) &LoadedImage
+  );
+
+  if (Status == EFI_SUCCESS) {
+    EFI_DEVICE_PATH_PROTOCOL* DevicePath;
+
+    Status = gBS->HandleProtocol(
+      ImageHandle,
+      &gEfiLoadedImageDevicePathProtocolGuid,
+      (VOID**) &DevicePath
+    );
+
+    if (Status == EFI_SUCCESS) {
+      Print(L"Image device: %s\n", ConvertDevicePathToText(DevicePath, FALSE, TRUE));
+      Print(L"Image file: %s\n",  ConvertDevicePathToText(LoadedImage->FilePath, FALSE, TRUE));	// EFI_DEVICE_PATH_PROTOCOL *FilePath
+      Print(L"Image Base: %X\n", LoadedImage->ImageBase);
+      Print(L"Image Size: %X\n", LoadedImage->ImageSize);
+    } else {
+      Print(L"Can't get EFI_LOADED_IMAGE_PROTOCOL, Status=%r\n", Status);
+    }
+  } else {
+    Print(L"Can't get EFI_DEVICE_PATH_PROTOCOL, Status=%r\n", Status);
+  }
+  return EFI_SUCCESS;
+}
diff --git a/Lesson_17/UefiLessonsPkg/ImageInfo/ImageInfo.inf b/Lesson_17/UefiLessonsPkg/ImageInfo/ImageInfo.inf
new file mode 100644
index 0000000..0ce54a6
--- /dev/null
+++ b/Lesson_17/UefiLessonsPkg/ImageInfo/ImageInfo.inf
@@ -0,0 +1,22 @@
+[Defines]
+  INF_VERSION                    = 1.25
+  BASE_NAME                      = ImageInfo
+  FILE_GUID                      = b68d3472-70c7-4928-841b-6566032e0a23
+  MODULE_TYPE                    = UEFI_APPLICATION
+  VERSION_STRING                 = 1.0
+  ENTRY_POINT                    = UefiMain
+
+[Sources]
+  ImageInfo.c
+
+[Packages]
+  MdePkg/MdePkg.dec
+
+[LibraryClasses]
+  UefiApplicationEntryPoint
+  UefiLib
+
+[Protocols]
+  gEfiLoadedImageProtocolGuid
+  gEfiLoadedImageDevicePathProtocolGuid
+
diff --git a/Lesson_17/UefiLessonsPkg/ListVariables/ListVariables.c b/Lesson_17/UefiLessonsPkg/ListVariables/ListVariables.c
new file mode 100644
index 0000000..1f3ef4a
--- /dev/null
+++ b/Lesson_17/UefiLessonsPkg/ListVariables/ListVariables.c
@@ -0,0 +1,46 @@
+#include <Library/UefiBootServicesTableLib.h>
+#include <Library/UefiLib.h>
+
+
+#include <Library/MemoryAllocationLib.h>
+#include <Library/UefiRuntimeServicesTableLib.h>
+
+INTN EFIAPI ShellAppMain(IN UINTN Argc, IN CHAR16 **Argv)
+{
+  EFI_GUID VendorGuid;
+  UINTN VariableNameSize = sizeof (CHAR16);
+  CHAR16* VariableName = AllocateZeroPool(sizeof(CHAR16));
+  if (VariableName == NULL) {
+    Print(L"Error on AllocateZeroPool call\n");
+    return EFI_OUT_OF_RESOURCES;
+  }
+
+  while (TRUE)
+  {
+    UINTN VariableNameSizeOld = VariableNameSize;
+    EFI_STATUS Status = gRT->GetNextVariableName(&VariableNameSize, VariableName, &VendorGuid);
+    if (Status == EFI_SUCCESS) {
+      Print(L"%g: %s\n", VendorGuid, VariableName);
+    } else if (Status == EFI_BUFFER_TOO_SMALL) {
+      VariableName = ReallocatePool(VariableNameSizeOld, VariableNameSize, VariableName);
+      if (VariableName == NULL) {
+        Print(L"Error on ReallocatePool call\n");
+        return EFI_OUT_OF_RESOURCES;
+      }
+      Status = gRT->GetNextVariableName(&VariableNameSize, VariableName, &VendorGuid);
+      if (Status == EFI_SUCCESS) {
+        Print(L"%g: %s\n", VendorGuid, VariableName);
+      } else {
+        Print(L"Error on 'gRT->GetNextVariableName' call: %s\n", Status);
+        return Status;
+      }
+    } else if (Status == EFI_NOT_FOUND) {
+      FreePool(VariableName);
+      return EFI_SUCCESS;
+    } else {
+      Print(L"Error on 'gRT->GetNextVariableName' call: %s\n", Status);
+      return Status;
+    }
+  }
+  return EFI_SUCCESS;
+}
diff --git a/Lesson_17/UefiLessonsPkg/ListVariables/ListVariables.inf b/Lesson_17/UefiLessonsPkg/ListVariables/ListVariables.inf
new file mode 100644
index 0000000..14e9fa2
--- /dev/null
+++ b/Lesson_17/UefiLessonsPkg/ListVariables/ListVariables.inf
@@ -0,0 +1,19 @@
+[Defines]
+  INF_VERSION                    = 1.25
+  BASE_NAME                      = ListVariables
+  FILE_GUID                      = d66f68b2-3591-45af-bf5d-519152b9d877
+  MODULE_TYPE                    = UEFI_APPLICATION
+  VERSION_STRING                 = 1.0
+  ENTRY_POINT                    = ShellCEntryLib
+
+[Sources]
+  ListVariables.c
+
+[Packages]
+  MdePkg/MdePkg.dec
+
+[LibraryClasses]
+  UefiApplicationEntryPoint
+  UefiLib
+  ShellCEntryLib
+
diff --git a/Lesson_17/UefiLessonsPkg/MemoryInfo/MemoryInfo.c b/Lesson_17/UefiLessonsPkg/MemoryInfo/MemoryInfo.c
new file mode 100644
index 0000000..8c3bcf2
--- /dev/null
+++ b/Lesson_17/UefiLessonsPkg/MemoryInfo/MemoryInfo.c
@@ -0,0 +1,215 @@
+#include <Library/UefiBootServicesTableLib.h>
+#include <Library/UefiLib.h>
+
+// for SetMem
+#include <Library/BaseMemoryLib.h>
+
+#include <Protocol/ShellParameters.h> 
+
+const CHAR16 *memory_types[] = { 
+    L"EfiReservedMemoryType", 
+    L"EfiLoaderCode", 
+    L"EfiLoaderData", 
+    L"EfiBootServicesCode", 
+    L"EfiBootServicesData", 
+    L"EfiRuntimeServicesCode", 
+    L"EfiRuntimeServicesData", 
+    L"EfiConventionalMemory", 
+    L"EfiUnusableMemory", 
+    L"EfiACPIReclaimMemory", 
+    L"EfiACPIMemoryNVS", 
+    L"EfiMemoryMappedIO", 
+    L"EfiMemoryMappedIOPortSpace", 
+    L"EfiPalCode",
+    L"EfiPersistentMemory",
+    L"EfiMaxMemoryType"
+};
+
+
+const CHAR16 *memory_types_OS_view[] = { 
+    L"reserved", // L"EfiReservedMemoryType", 
+    L"usable",   // L"EfiLoaderCode", 
+    L"usable",   // L"EfiLoaderData", 
+    L"usable",   // L"EfiBootServicesCode", 
+    L"usable",   // L"EfiBootServicesData", 
+    L"reserved", // L"EfiRuntimeServicesCode", 
+    L"reserved", // L"EfiRuntimeServicesData", 
+    L"usable",   // L"EfiConventionalMemory", 
+    L"reserved", // L"EfiUnusableMemory", 
+    L"ACPI data",// L"EfiACPIReclaimMemory", 
+    L"ACPI NVS", // L"EfiACPIMemoryNVS", 
+    L"reserved", // L"EfiMemoryMappedIO", 
+    L"reserved", // L"EfiMemoryMappedIOPortSpace", 
+    L"reserved", // L"EfiPalCode",
+    L"usable",   // L"EfiPersistentMemory",
+    L"usable",   // L"EfiMaxMemoryType"
+};
+
+
+const CHAR16 * 
+memory_type_to_str(UINT32 type) 
+{ 
+    if (type > sizeof(memory_types)/sizeof(CHAR16 *)) 
+        return L"Unknown"; 
+
+    return memory_types[type]; 
+}
+
+const CHAR16 *
+memory_type_to_str_OS_view(UINT32 type)
+{
+    if (type > sizeof(memory_types_OS_view)/sizeof(CHAR16 *)) 
+        return L"Unknown"; 
+
+    return memory_types_OS_view[type]; 
+}
+
+#define ATTRIBUTE_STR_SIZE 50
+
+#define CHECK_EFI_MEMORY_ATTRIBUTE(attr) if (attrs & EFI_MEMORY_##attr) { \
+                                           StrCpyS(&str[i], ATTRIBUTE_STR_SIZE, L" "#attr); \
+                                           i+=StrLen(L" "#attr); \
+                                         }
+
+const CHAR16 *
+memory_attrs_to_str(CHAR16* str, UINT64 attrs)
+{
+  int i=0;
+  SetMem((VOID *)str, sizeof(str), 0);
+
+  CHECK_EFI_MEMORY_ATTRIBUTE(UC)
+  CHECK_EFI_MEMORY_ATTRIBUTE(WC)
+  CHECK_EFI_MEMORY_ATTRIBUTE(WT)
+  CHECK_EFI_MEMORY_ATTRIBUTE(WB)
+  CHECK_EFI_MEMORY_ATTRIBUTE(UCE)
+  CHECK_EFI_MEMORY_ATTRIBUTE(WP)
+  CHECK_EFI_MEMORY_ATTRIBUTE(RP)
+  CHECK_EFI_MEMORY_ATTRIBUTE(XP)
+  CHECK_EFI_MEMORY_ATTRIBUTE(NV)
+  CHECK_EFI_MEMORY_ATTRIBUTE(MORE_RELIABLE)
+  CHECK_EFI_MEMORY_ATTRIBUTE(RO)
+  CHECK_EFI_MEMORY_ATTRIBUTE(SP)
+  CHECK_EFI_MEMORY_ATTRIBUTE(CPU_CRYPTO)
+  CHECK_EFI_MEMORY_ATTRIBUTE(RUNTIME)
+
+  return str;
+}
+
+EFI_STATUS
+EFIAPI
+UefiMain (
+  IN EFI_HANDLE        ImageHandle,
+  IN EFI_SYSTEM_TABLE  *SystemTable
+  )
+{
+  UINTN MemoryMapSize = 0;
+  EFI_MEMORY_DESCRIPTOR* MemoryMap = NULL;
+  UINTN MapKey;
+  UINTN DescriptorSize;
+  UINT32 DescriptorVersion;
+
+  EFI_STATUS Status;
+
+
+  EFI_SHELL_PARAMETERS_PROTOCOL* ShellParameters;
+
+  Status = gBS->HandleProtocol(
+    ImageHandle,
+    &gEfiShellParametersProtocolGuid,
+    (VOID **) &ShellParameters
+  );
+
+  BOOLEAN full=FALSE;
+  if (Status == EFI_SUCCESS) {
+    if (ShellParameters->Argc == 2) {
+      if (!StrCmp(ShellParameters->Argv[1], L"full")) {
+        full=TRUE;
+      }
+    }
+  }
+
+
+  Status = gBS->GetMemoryMap(
+        &MemoryMapSize,
+        MemoryMap,
+        &MapKey,
+        &DescriptorSize,
+        &DescriptorVersion
+  );
+
+  if (Status == EFI_BUFFER_TOO_SMALL) {
+    Status = gBS->AllocatePool(
+          EfiBootServicesData,
+          MemoryMapSize,
+          (void**)&MemoryMap
+    );
+
+    if (EFI_ERROR(Status)) {
+      Print(L"AllocatePool error: %r\n", Status);
+      return Status;
+    }
+
+    Status = gBS->GetMemoryMap(
+          &MemoryMapSize,
+          MemoryMap,
+          &MapKey,
+          &DescriptorSize,
+          &DescriptorVersion
+    );
+
+    if (!EFI_ERROR(Status))
+    {
+      EFI_MEMORY_DESCRIPTOR* desc = MemoryMap;
+      EFI_MEMORY_DESCRIPTOR* next_desc;
+      int i = 0;
+      while ((UINT8 *)desc < (UINT8 *)MemoryMap + MemoryMapSize) {
+        UINTN PAGE_SIZE = 4096;
+        UINTN mapping_size =(UINTN) desc->NumberOfPages * PAGE_SIZE;
+
+        UINT64 Start = desc->PhysicalStart;
+
+        next_desc = (EFI_MEMORY_DESCRIPTOR *)((UINT8 *)desc + DescriptorSize);
+        if (!full) {
+	  while ((UINT8 *)next_desc < (UINT8 *)MemoryMap + MemoryMapSize) {
+	    mapping_size =(UINTN) desc->NumberOfPages * PAGE_SIZE;
+	    if ((desc->PhysicalStart + mapping_size) == (next_desc->PhysicalStart)) {
+
+              if (desc->Type != next_desc->Type) {
+                if (StrCmp(memory_type_to_str_OS_view(desc->Type), 
+                           memory_type_to_str_OS_view(next_desc->Type)))
+                  break;
+                }
+
+                desc=next_desc;
+	        next_desc = (EFI_MEMORY_DESCRIPTOR *)((UINT8 *)next_desc + DescriptorSize);
+	    } else {
+	        break;
+	    }
+	  }
+        }
+
+        if (full) {
+          CHAR16 str[ATTRIBUTE_STR_SIZE];
+          Print(L"[#%02d] Type: %s  Attr: %s\n", i++, 
+            memory_type_to_str(desc->Type), memory_attrs_to_str(str, desc->Attribute));
+          Print(L"      Phys: %016llx-%016llx\n", Start, Start + mapping_size - 1);
+        }
+        else {
+          Print(L" [mem: %016llx-%016llx] %s\n", Start, desc->PhysicalStart + mapping_size - 1,
+            memory_type_to_str_OS_view(desc->Type) );
+        }
+
+        desc = next_desc;
+      }
+
+      gBS->FreePool(MemoryMap);
+    } else {
+      Print(L"GetMemoryMap with buffer error: %r\n", Status);
+    }
+  } else {
+    Print(L"GetMemoryMap without buffer error: %r\n", Status);
+  }
+
+  return Status;
+}
+
diff --git a/Lesson_17/UefiLessonsPkg/MemoryInfo/MemoryInfo.inf b/Lesson_17/UefiLessonsPkg/MemoryInfo/MemoryInfo.inf
new file mode 100644
index 0000000..777010d
--- /dev/null
+++ b/Lesson_17/UefiLessonsPkg/MemoryInfo/MemoryInfo.inf
@@ -0,0 +1,21 @@
+[Defines]
+  INF_VERSION                    = 1.25
+  BASE_NAME                      = MemoryInfo
+  FILE_GUID                      = d2ce1d65-603e-4b48-b3e1-fe65d5d0bca8
+  MODULE_TYPE                    = UEFI_APPLICATION
+  VERSION_STRING                 = 1.0
+  ENTRY_POINT                    = UefiMain
+
+[Sources]
+  MemoryInfo.c
+
+[Packages]
+  MdePkg/MdePkg.dec
+
+[LibraryClasses]
+  UefiApplicationEntryPoint
+  UefiLib
+
+[Protocols]
+  gEfiShellParametersProtocolGuid
+
diff --git a/Lesson_17/UefiLessonsPkg/ShowBootVariables/ShowBootVariables.c b/Lesson_17/UefiLessonsPkg/ShowBootVariables/ShowBootVariables.c
new file mode 100644
index 0000000..7f6b58c
--- /dev/null
+++ b/Lesson_17/UefiLessonsPkg/ShowBootVariables/ShowBootVariables.c
@@ -0,0 +1,93 @@
+#include <Library/UefiBootServicesTableLib.h>
+#include <Library/UefiLib.h>
+
+#include <Library/MemoryAllocationLib.h>
+#include <Library/UefiRuntimeServicesTableLib.h>
+
+#include <Library/DevicePathLib.h>
+#include <Library/PrintLib.h>
+
+
+EFI_STATUS
+GetNvramVariable( CHAR16   *VariableName,
+                  EFI_GUID *VariableOwnerGuid, 
+                  VOID     **Buffer,
+                  UINTN    *BufferSize)
+{
+    UINTN Size = 0;
+    *BufferSize = 0;
+
+    EFI_STATUS Status = gRT->GetVariable(VariableName, VariableOwnerGuid, NULL, &Size, NULL);
+    if (Status != EFI_BUFFER_TOO_SMALL) {
+        Print(L"Error! 'gRT->GetVariable' call returned %r\n", Status);
+        return Status;
+    }
+
+    *Buffer = AllocateZeroPool(Size);
+    if (!Buffer) {
+        Print(L"Error! 'AllocateZeroPool' call returned %r\n", Status);
+        return EFI_OUT_OF_RESOURCES;
+    }
+
+    Status = gRT->GetVariable(VariableName, VariableOwnerGuid, NULL, &Size, *Buffer);
+    if (Status == EFI_SUCCESS) {
+        *BufferSize = Size;
+    } else {
+        FreePool( *Buffer );
+        *Buffer = NULL;
+    }
+
+    return Status;
+}
+
+
+VOID PrintBootOption(CHAR16* BootOptionName)
+{
+  UINTN OptionSize;
+  UINT8* Buffer;
+ 
+  EFI_STATUS Status = GetNvramVariable(BootOptionName, &gEfiGlobalVariableGuid, (VOID**)&Buffer, &OptionSize);
+  if (Status == EFI_SUCCESS) {
+      EFI_LOAD_OPTION* LoadOption = (EFI_LOAD_OPTION*) Buffer;
+      CHAR16* Description = (CHAR16*)(Buffer + sizeof (EFI_LOAD_OPTION));
+      UINTN DescriptionSize = StrSize(Description);
+
+      Print(L"%s\n", Description);
+      if (LoadOption->FilePathListLength != 0) {
+        VOID* FilePathList = (UINT8 *)Description + DescriptionSize;
+        CHAR16* DevPathString = ConvertDevicePathToText(FilePathList, TRUE, FALSE);
+        Print(L"%s\n", DevPathString);
+      }
+  } else {
+    Print(L"Can't get %s variable\n", BootOptionName);
+  }
+}
+
+
+INTN EFIAPI ShellAppMain(IN UINTN Argc, IN CHAR16 **Argv)
+{
+  UINTN OptionSize;
+  EFI_STATUS Status;
+
+  UINT16* BootCurrent;
+  Status = GetNvramVariable(L"BootCurrent", &gEfiGlobalVariableGuid, (VOID**)&BootCurrent, &OptionSize);
+  if (Status != EFI_SUCCESS) {
+    Print(L"Can't get BootCurrent variable\n");
+  }
+
+  UINT16* BootOrderArray;
+  Status = GetNvramVariable(L"BootOrder", &gEfiGlobalVariableGuid, (VOID**)&BootOrderArray, &OptionSize);
+  if (Status == EFI_SUCCESS) {
+    for (UINTN i=0; i<(OptionSize/sizeof(UINT16)); i++) {
+      CHAR16 BootOptionStr[sizeof("Boot####")+1];
+      UnicodeSPrint(BootOptionStr, (sizeof("Boot####")+1)*sizeof(CHAR16), L"Boot%04x", BootOrderArray[i]);
+      Print(L"%s%s\n", BootOptionStr, (BootOrderArray[i] == *BootCurrent)? L"*" : L"" );
+      PrintBootOption(BootOptionStr);
+      Print(L"\n");
+    }
+  } else {
+    Print(L"Can't get BootOrder variable\n");
+  }
+
+  return EFI_SUCCESS;
+}
diff --git a/Lesson_17/UefiLessonsPkg/ShowBootVariables/ShowBootVariables.inf b/Lesson_17/UefiLessonsPkg/ShowBootVariables/ShowBootVariables.inf
new file mode 100644
index 0000000..d2cfba9
--- /dev/null
+++ b/Lesson_17/UefiLessonsPkg/ShowBootVariables/ShowBootVariables.inf
@@ -0,0 +1,19 @@
+[Defines]
+  INF_VERSION                    = 1.25
+  BASE_NAME                      = ShowBootVariables
+  FILE_GUID                      = 31266d12-9c60-478e-905e-05d117a3a9df
+  MODULE_TYPE                    = UEFI_APPLICATION
+  VERSION_STRING                 = 1.0
+  ENTRY_POINT                    = ShellCEntryLib
+
+[Sources]
+  ShowBootVariables.c
+
+[Packages]
+  MdePkg/MdePkg.dec
+
+[LibraryClasses]
+  UefiApplicationEntryPoint
+  UefiLib
+  ShellCEntryLib
+
diff --git a/Lesson_17/UefiLessonsPkg/SimpleShellApp/SimpleShellApp.c b/Lesson_17/UefiLessonsPkg/SimpleShellApp/SimpleShellApp.c
new file mode 100644
index 0000000..b13aa6c
--- /dev/null
+++ b/Lesson_17/UefiLessonsPkg/SimpleShellApp/SimpleShellApp.c
@@ -0,0 +1,14 @@
+#include <Library/UefiBootServicesTableLib.h>
+#include <Library/UefiLib.h>
+
+INTN EFIAPI ShellAppMain(IN UINTN Argc, IN CHAR16 **Argv)
+{
+//  SystemTable->ConOut->OutputString(SystemTable->ConOut, L"Hello World!\n");
+  gST->ConOut->OutputString(gST->ConOut, L"Hello again!\n");
+  Print(L"Bye!\n");
+
+  for (UINTN i=Argc; i>0; i--) {
+    Print(L"Arg[%d]=%s\n", Argc-i, Argv[Argc-i]);
+  }
+  return 0;
+}
diff --git a/Lesson_17/UefiLessonsPkg/SimpleShellApp/SimpleShellApp.inf b/Lesson_17/UefiLessonsPkg/SimpleShellApp/SimpleShellApp.inf
new file mode 100644
index 0000000..013bf4e
--- /dev/null
+++ b/Lesson_17/UefiLessonsPkg/SimpleShellApp/SimpleShellApp.inf
@@ -0,0 +1,19 @@
+[Defines]
+  INF_VERSION                    = 1.25
+  BASE_NAME                      = SimpleShellApp
+  FILE_GUID                      = 2afd1202-545e-4f8d-b8fb-bc179e84ddc8
+  MODULE_TYPE                    = UEFI_APPLICATION
+  VERSION_STRING                 = 1.0
+  ENTRY_POINT                    = ShellCEntryLib
+
+[Sources]
+  SimpleShellApp.c
+
+[Packages]
+  MdePkg/MdePkg.dec
+
+[LibraryClasses]
+  UefiApplicationEntryPoint
+  UefiLib
+  ShellCEntryLib
+
diff --git a/Lesson_17/UefiLessonsPkg/SimplestApp/SimplestApp.c b/Lesson_17/UefiLessonsPkg/SimplestApp/SimplestApp.c
new file mode 100644
index 0000000..8bdf500
--- /dev/null
+++ b/Lesson_17/UefiLessonsPkg/SimplestApp/SimplestApp.c
@@ -0,0 +1,10 @@
+EFI_STATUS
+EFIAPI
+UefiMain (
+  IN EFI_HANDLE        ImageHandle,
+  IN EFI_SYSTEM_TABLE  *SystemTable
+  )
+{
+  return EFI_SUCCESS;
+}
+
diff --git a/Lesson_17/UefiLessonsPkg/SimplestApp/SimplestApp.inf b/Lesson_17/UefiLessonsPkg/SimplestApp/SimplestApp.inf
new file mode 100644
index 0000000..7d4bae2
--- /dev/null
+++ b/Lesson_17/UefiLessonsPkg/SimplestApp/SimplestApp.inf
@@ -0,0 +1,16 @@
+[Defines]
+  INF_VERSION                    = 1.25
+  BASE_NAME                      = SimplestApp
+  FILE_GUID                      = 4a298956-fbe0-47fb-ae3a-2d5a0a959a26
+  MODULE_TYPE                    = UEFI_APPLICATION
+  VERSION_STRING                 = 1.0
+  ENTRY_POINT                    = UefiMain
+
+[Sources]
+  SimplestApp.c
+
+[Packages]
+  MdePkg/MdePkg.dec
+
+[LibraryClasses]
+  UefiApplicationEntryPoint
diff --git a/Lesson_17/UefiLessonsPkg/UefiLessonsPkg.dec b/Lesson_17/UefiLessonsPkg/UefiLessonsPkg.dec
new file mode 100644
index 0000000..d37e955
--- /dev/null
+++ b/Lesson_17/UefiLessonsPkg/UefiLessonsPkg.dec
@@ -0,0 +1,22 @@
+[Defines]

+  DEC_SPECIFICATION              = 0x00010005

+  PACKAGE_NAME                   = UefiLessonsPkg

+  PACKAGE_GUID                   = 7e7edbba-ca2c-4177-a3f0-d3371358773a

+  PACKAGE_VERSION                = 1.01

+

+[Includes]

+

+[LibraryClasses]

+

+[Guids]

+  # FILE_GUID as defined in UefiLessonsPkg/HelloWorld/HelloWorld.inf

+  gHelloWorldFileGuid            = {0x2e55fa38, 0xf148, 0x42d3, {0xaf, 0x90, 0x1b, 0xe2, 0x47, 0x32, 0x3e, 0x30}}

+

+[Protocols]

+

+[PcdsFeatureFlag]

+

+[PcdsFixedAtBuild]

+

+[PcdsFixedAtBuild, PcdsPatchableInModule, PcdsDynamic, PcdsDynamicEx]

+

diff --git a/Lesson_17/UefiLessonsPkg/UefiLessonsPkg.dsc b/Lesson_17/UefiLessonsPkg/UefiLessonsPkg.dsc
new file mode 100644
index 0000000..5a3ae1c
--- /dev/null
+++ b/Lesson_17/UefiLessonsPkg/UefiLessonsPkg.dsc
@@ -0,0 +1,36 @@
+[Defines]
+  DSC_SPECIFICATION              = 0x0001001C
+  PLATFORM_GUID                  = 3db7270f-ffac-4139-90a4-0ae68f3f8167
+  PLATFORM_VERSION               = 0.01
+  PLATFORM_NAME                  = UefiLessonsPkg
+  SKUID_IDENTIFIER               = DEFAULT
+  SUPPORTED_ARCHITECTURES        = X64
+  BUILD_TARGETS                  = RELEASE
+
+
+[LibraryClasses]
+  UefiApplicationEntryPoint|MdePkg/Library/UefiApplicationEntryPoint/UefiApplicationEntryPoint.inf
+  UefiBootServicesTableLib|MdePkg/Library/UefiBootServicesTableLib/UefiBootServicesTableLib.inf
+  DebugLib|MdePkg/Library/UefiDebugLibConOut/UefiDebugLibConOut.inf
+  BaseLib|MdePkg/Library/BaseLib/BaseLib.inf
+  PcdLib|MdePkg/Library/BasePcdLibNull/BasePcdLibNull.inf
+  BaseMemoryLib|MdePkg/Library/BaseMemoryLib/BaseMemoryLib.inf
+  RegisterFilterLib|MdePkg/Library/RegisterFilterLibNull/RegisterFilterLibNull.inf
+  PrintLib|MdePkg/Library/BasePrintLib/BasePrintLib.inf
+  DebugPrintErrorLevelLib|MdePkg/Library/BaseDebugPrintErrorLevelLib/BaseDebugPrintErrorLevelLib.inf
+  UefiLib|MdePkg/Library/UefiLib/UefiLib.inf
+  MemoryAllocationLib|MdePkg/Library/UefiMemoryAllocationLib/UefiMemoryAllocationLib.inf
+  DevicePathLib|MdePkg/Library/UefiDevicePathLib/UefiDevicePathLib.inf
+  UefiRuntimeServicesTableLib|MdePkg/Library/UefiRuntimeServicesTableLib/UefiRuntimeServicesTableLib.inf
+  ShellCEntryLib|ShellPkg/Library/UefiShellCEntryLib/UefiShellCEntryLib.inf
+
+[Components]
+  UefiLessonsPkg/SimplestApp/SimplestApp.inf
+  UefiLessonsPkg/HelloWorld/HelloWorld.inf
+  UefiLessonsPkg/ImageHandle/ImageHandle.inf
+  UefiLessonsPkg/ImageInfo/ImageInfo.inf
+  UefiLessonsPkg/MemoryInfo/MemoryInfo.inf
+  UefiLessonsPkg/SimpleShellApp/SimpleShellApp.inf
+  UefiLessonsPkg/ListVariables/ListVariables.inf
+  UefiLessonsPkg/ShowBootVariables/ShowBootVariables.inf
+
diff --git a/README.md b/README.md
index e850554..40fd78e 100644
--- a/README.md
+++ b/README.md
@@ -19,4 +19,5 @@ Lessons description:
 - Lesson 14: Get all variable names and GUIDs with the `gRT->GetNextVariableName` API
 - Lesson 15: Get and parse boot variables (BootOrder/BootCurrent/BootXXXX) with the `gRT->GetVariable` API
 - Lesson 16: Build our own boot option inside OVMF image similar to th UEFI shell app
+- Lesson 17: Add `WaitForEvent` function to our boot option app to see its output on booting