Move lessons to separate folder

Signed-off-by: Konstantin Aladyshev <aladyshev22@gmail.com>

1 files changed, 225 insertions, 0 deletions

diff --git a/Lessons/Lesson_23/README.md b/Lessons/Lesson_23/README.md
new file mode 100644
index 0000000..bae429d
--- /dev/null
+++ b/Lessons/Lesson_23/README.md
@@ -0,0 +1,225 @@
+Now let's explore `PatchableInModule` PCD.
+
+Add PCD to DEC file UefiLessonsPkg/UefiLessonsPkg.dec:
+```
+[PcdsPatchableInModule]
+  gUefiLessonsPkgTokenSpaceGuid.PcdMyPatchableVar32|0x31313131|UINT32|0x00000004
+```
+Populate it to INF UefiLessonsPkg/PCDLesson/PCDLesson.inf:
+```
+[PatchPcd]
+  gUefiLessonsPkgTokenSpaceGuid.PcdMyPatchableVar32
+```
+
+To get a value of PCD in a *.c file either `PatchPcdGet` or generic `PcdGet` should be used.
+
+Let's test both methods:
+```
+Print(L"PcdMyPatchableVar32=%d\n", PatchPcdGet32(PcdMyPatchableVar32));
+Print(L"PcdMyPatchableVar32=%d\n", PcdGet32(PcdMyPatchableVar32));
+```
+
+Now build and look to AutoGen files:
+
+Build/UefiLessonsPkg/RELEASE_GCC5/X64/UefiLessonsPkg/PCDLesson/PCDLesson/DEBUG/AutoGen.h
+```
+#define _PCD_TOKEN_PcdMyPatchableVar32  0U
+#define _PCD_PATCHABLE_VALUE_PcdMyPatchableVar32  ((UINT32)0x31313131U)
+extern volatile   UINT32  _gPcd_BinaryPatch_PcdMyPatchableVar32;
+#define _PCD_GET_MODE_32_PcdMyPatchableVar32  _gPcd_BinaryPatch_PcdMyPatchableVar32
+#define _PCD_PATCHABLE_PcdMyPatchableVar32_SIZE 4
+#define _PCD_GET_MODE_SIZE_PcdMyPatchableVar32  _gPcd_BinaryPatch_Size_PcdMyPatchableVar32
+extern UINTN _gPcd_BinaryPatch_Size_PcdMyPatchableVar32;
+#define _PCD_SET_MODE_32_PcdMyPatchableVar32(Value)  (_gPcd_BinaryPatch_PcdMyPatchableVar32 = (Value))
+#define _PCD_SET_MODE_32_S_PcdMyPatchableVar32(Value)  ((_gPcd_BinaryPatch_PcdMyPatchableVar32 = (Value)), RETURN_SUCCESS)
+```
+Build/UefiLessonsPkg/RELEASE_GCC5/X64/UefiLessonsPkg/PCDLesson/PCDLesson/DEBUG/AutoGen.c
+```
+volatile  UINT32 _gPcd_BinaryPatch_PcdMyPatchableVar32 = _PCD_PATCHABLE_VALUE_PcdMyPatchableVar32;
+GLOBAL_REMOVE_IF_UNREFERENCED UINTN _gPcd_BinaryPatch_Size_PcdMyPatchableVar32 = 4;
+```
+
+So in this case our call to `PcdGet32(PcdMyPatchableVar32)` would be expanded to:
+```
+PcdGet32(PcdMyPatchableVar32) --> _PCD_GET_MODE_32_PcdMyPatchableVar32 --> _gPcd_BinaryPatch_PcdMyPatchableVar32
+```
+This variable would be assigned in `AutoGen.c`:
+```
+volatile  UINT32 _gPcd_BinaryPatch_PcdMyPatchableVar32 = ((UINT32)0x31313131U);
+```
+So the main difference from the FixedAtBuild and FeatureFlag PCDs is that variable defined as `volatile` and set functions aren't blocked.
+
+Let's try to set our PCD then. As with get, there are two possibilities. You can use either `PatchPcdSet<Type>` or generic `PcdSet<Type>S`.
+
+Keep in mind that `PcdSet32S` unravels to a macro returning a value.
+https://github.com/tianocore/edk2/blob/master/MdePkg/Include/Library/PcdLib.h:
+```
+#define PcdSet32S(TokenName, Value)         _PCD_SET_MODE_32_S_##TokenName    ((Value))
+```
+Therefore:
+```
+PcdSet32S(PcdMyPatchableVar32, 44) -->  _PCD_SET_MODE_32_S_PcdMyPatchableVar32 ((Value)) --> ((_gPcd_BinaryPatch_PcdMyPatchableVar32 = (Value)), RETURN_SUCCESS)
+```
+
+So if you don't want such error:
+```
+/home/kostr/tiano/edk2/Build/UefiLessonsPkg/RELEASE_GCC5/X64/UefiLessonsPkg/PCDLesson/PCDLesson/DEBUG/AutoGen.h:108:106: error: right-hand operand of comma expression has no effect [-Werror=unused-value]
+  108 | #define _PCD_SET_MODE_32_S_PcdMyPatchableVar32(Value)  ((_gPcd_BinaryPatch_PcdMyPatchableVar32 = (Value)), RETURN_SUCCESS)
+      |                                                        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~.
+```
+You should use something like this:
+```
+RETURN_STATUS PcdStatus = PcdSet32S(PcdMyPatchableVar32, 44);
+Print(L"PcdStatus=%r\n", PcdStatus);
+```
+
+Alternatively you can use `PatchPcdSet32` which don't require such thing as it is defined as follows:
+```
+#define PatchPcdSet32(TokenName, Value)     (_gPcd_BinaryPatch_##TokenName = (Value))
+```
+
+Test both set methods in app code:
+```
+Print(L"PcdMyPatchableVar32=0x%x\n", PcdGet32(PcdMyPatchableVar32));
+RETURN_STATUS PcdStatus = PcdSet32S(PcdMyPatchableVar32, 44);
+Print(L"PcdStatus=%r\n", PcdStatus);
+Print(L"PcdMyPatchableVar32=%d\n", PcdGet32(PcdMyPatchableVar32));
+PatchPcdSet32(PcdMyPatchableVar32, 45);
+Print(L"PcdMyPatchableVar32=%d\n", PatchPcdGet32(PcdMyPatchableVar32));
+```
+
+
+Now if you execute our app under OVMF prints for patchable PCDs would output:
+```
+PcdMyPatchableVar32=0x31313131
+PcdStatus=Success
+PcdMyPatchableVar32=44
+PcdMyPatchableVar32=45
+```
+
+_________________________________
+
+In case you've wondered why I've assigned a hex value for PCD default value or why this PCD type is named `PatchableInModule` this section is for you.
+
+This PCD type is named like that because the value of this PCD can be changed in a binary PE/COFF image (*.efi file). To do this two utilities are used:
+- `GenPatchPcdTable` - this tool is used to get the patchable PCD offset for the EFI image by parsing the map file
+- `PatchPcdValue` - this tool is used to actually patch PCD value
+
+You can download rtf manuals for these utilities from edk2 repo:
+-https://github.com/tianocore/edk2/blob/master/BaseTools/UserManuals/GenPatchPcdTable_Utility_Man_Page.rtf
+-https://github.com/tianocore/edk2/blob/master/BaseTools/UserManuals/PatchPcdValue_Utility_Man_Page.rtf
+
+Let's start with `GenPatchPcdTable`. First check out help for this tool:
+```
+$ ./BaseTools/BinWrappers/PosixLike/GenPatchPcdTable -h
+Usage: GenPatchPcdTable.py -m <MapFile> -e <EfiFile> -o <OutFile>
+
+Copyright (c) 2008 - 2018, Intel Corporation. All rights reserved.
+
+Options:
+  --version             show program's version number and exit
+  -h, --help            show this help message and exit
+  -m MAPFILE, --mapfile=MAPFILE
+                        Absolute path of module map file.
+  -e EFIFILE, --efifile=EFIFILE
+                        Absolute path of EFI binary file.
+  -o OUTFILE, --outputfile=OUTFILE
+                        Absolute path of output file to store the got
+                        patchable PCD table.
+```
+Now let's create a `PatchPcdTable` for our app:
+
+For the *.efi file we can use one of:
+```
+Build/UefiLessonsPkg/RELEASE_GCC5/X64/PCDLesson.efi 
+Build/UefiLessonsPkg/RELEASE_GCC5/X64/UefiLessonsPkg/PCDLesson/PCDLesson/OUTPUT/PCDLesson.efi
+Build/UefiLessonsPkg/RELEASE_GCC5/X64/UefiLessonsPkg/PCDLesson/PCDLesson/DEBUG/PCDLesson.efi
+```
+For the *.map file we can use one of:
+```
+Build/UefiLessonsPkg/RELEASE_GCC5/X64/UefiLessonsPkg/PCDLesson/PCDLesson/DEBUG/PCDLesson.map
+Build/UefiLessonsPkg/RELEASE_GCC5/X64/UefiLessonsPkg/PCDLesson/PCDLesson/OUTPUT/PCDLesson.map
+```
+In case you wonder how our PCD can be found in a map file, execute:
+```
+$ grep MyPatchableVar32 Build/UefiLessonsPkg/RELEASE_GCC5/X64/UefiLessonsPkg/PCDLesson/PCDLesson/DEBUG/PCDLesson.map -A2
+ .data._gPcd_BinaryPatch_PcdMyPatchableVar32
+                0x0000000000001920        0x4 /tmp/PCDLesson.dll.m6t8YL.ltrans0.ltrans.o
+ *fill*         0x0000000000001924        0xc
+```
+So as you can see the default value for our PCD is placed under 0x1920 offset.
+
+Now let's execute `GenPatchPcdTable` and create a file `PCDLessonPatchPcdTable` in app Build DEBUG folder:
+```
+./BaseTools/BinWrappers/PosixLike/GenPatchPcdTable \
+  -m Build/UefiLessonsPkg/RELEASE_GCC5/X64/UefiLessonsPkg/PCDLesson/PCDLesson/DEBUG/PCDLesson.map \
+  -e Build/UefiLessonsPkg/RELEASE_GCC5/X64/UefiLessonsPkg/PCDLesson/PCDLesson/DEBUG/PCDLesson.efi \
+  -o Build/UefiLessonsPkg/RELEASE_GCC5/X64/UefiLessonsPkg/PCDLesson/PCDLesson/DEBUG/PCDLessonPatchPcdTable
+```
+
+Checkout the created `PCDLessonPatchPcdTable` file.
+```
+$ cat Build/UefiLessonsPkg/RELEASE_GCC5/X64/UefiLessonsPkg/PCDLesson/PCDLesson/DEBUG/PCDLessonPatchPcdTable
+PCD Name                       Offset    Section Name
+PcdMyPatchableVar32            0x1920     .data
+```
+As you can see it has the same offset that we've seen in a map file.
+
+Now let's get a final look at our default PCD value in an *.elf file:
+```
+hexdump -s 0x1920 Build/UefiLessonsPkg/RELEASE_GCC5/X64/UefiLessonsPkg/PCDLesson/PCDLesson/DEBUG/PCDLesson.efi -n 4
+0001920 3131 3131
+0001924
+```
+
+Checkout help for the `PatchPcdValue` tool:
+```
+$ ./BaseTools/BinWrappers/PosixLike/PatchPcdValue -h
+Usage: PatchPcdValue.py -f Offset -u Value -t Type [-s MaxSize] <input_file>
+
+Copyright (c) 2010 - 2018, Intel Corporation. All rights reserved.
+
+Options:
+  -f PCDOFFSET, --offset=PCDOFFSET
+                        Start offset to the image is used to store PCD value.
+  -u PCDVALUE, --value=PCDVALUE
+                        PCD value will be updated into the image.
+  -t PCDTYPENAME, --type=PCDTYPENAME
+                        The name of PCD data type may be one of VOID*,BOOLEAN,
+                        UINT8, UINT16, UINT32, UINT64.
+  -s PCDMAXSIZE, --maxsize=PCDMAXSIZE
+                        Max size of data buffer is taken by PCD value.It must
+                        be set when PCD type is VOID*.
+  -v, --verbose         Run verbosely
+  -d LOGLEVEL, --debug=LOGLEVEL
+                        Run with debug information
+  -q, --quiet           Run quietly
+  -?                    show this help message and exit
+  --version             show program's version number and exit
+  -h, --help            show this help message and exit
+```
+
+Now use it to patch our PCD in an *.elf file:
+```
+./BaseTools/BinWrappers/PosixLike/PatchPcdValue \
+  --offset=0x1920 \
+  --value=0xDEADDEAD \
+  --type=UINT32 \
+  Build/UefiLessonsPkg/RELEASE_GCC5/X64/UefiLessonsPkg/PCDLesson/PCDLesson/DEBUG/PCDLesson.efi
+```
+Look at hexdump again:
+```
+$ hexdump -s 0x1920 Build/UefiLessonsPkg/RELEASE_GCC5/X64/UefiLessonsPkg/PCDLesson/PCDLesson/DEBUG/PCDLesson.efi -n 4
+0001920 dead dead
+0001924
+```
+We've successfully changed our PCD in a binary!
+
+Now if you execute our app under OVMF prints for patchable PCDs would output:
+```
+PcdMyPatchableVar32=0xDEADDEAD
+PcdStatus=Success
+PcdMyPatchableVar32=44
+PcdMyPatchableVar32=45
+```
+