Add lesson 26

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

2 files changed, 184 insertions, 0 deletions

diff --git a/Lesson_26/README.md b/Lesson_26/README.md
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+++ b/Lesson_26/README.md
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+
+```
+typedef struct {
+ EFI_TABLE_HEADER Hdr;
+ CHAR16 *FirmwareVendor;
+ UINT32 FirmwareRevision;
+ EFI_HANDLE ConsoleInHandle;
+ EFI_SIMPLE_TEXT_INPUT_PROTOCOL *ConIn;
+ EFI_HANDLE ConsoleOutHandle;
+ EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL *ConOut;
+ EFI_HANDLE StandardErrorHandle;
+ EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL *StdErr;
+ EFI_RUNTIME_SERVICES *RuntimeServices;
+ EFI_BOOT_SERVICES *BootServices;
+ UINTN NumberOfTableEntries;
+ EFI_CONFIGURATION_TABLE *ConfigurationTable;
+} EFI_SYSTEM_TABLE;
+```
+
+We've already used most of the fields of this structure. Now it is time to peek inside these fields:
+```
+UINTN NumberOfTableEntries;
+EFI_CONFIGURATION_TABLE *ConfigurationTable
+```
+According to the UEFI spec:
+```
+NumberOfTableEntries	The number of system configuration tables in the buffer ConfigurationTable.
+ConfigurationTable	A pointer to the system configuration tables. The number of entries in the table is NumberOfTableEntries.
+```
+
+As for EFI_CONFIGURATION_TABLE type:
+```
+EFI_CONFIGURATION_TABLE
+
+Summary:
+Contains a set of GUID/pointer pairs comprised of the ConfigurationTable field in the EFI System
+Table.
+Related Definitions
+typedef struct{
+ EFI_GUID VendorGuid;
+ VOID *VendorTable;
+} EFI_CONFIGURATION_TABLE;
+
+```
+
+Let's create a simple program `ShowTables` to look at tables available at OVMF:
+```
+#include <Library/UefiBootServicesTableLib.h>
+#include <Library/UefiLib.h>
+
+EFI_STATUS
+EFIAPI
+UefiMain (
+  IN EFI_HANDLE        ImageHandle,
+  IN EFI_SYSTEM_TABLE  *SystemTable
+  )
+{
+  for (UINTN i=0; i<SystemTable->NumberOfTableEntries; i++) {
+    Print(L"%g, %p\n", SystemTable->ConfigurationTable[i].VendorGuid,
+                       SystemTable->ConfigurationTable[i].VendorTable);
+  }
+  return EFI_SUCCESS;
+}
+```
+
+Build and execute it under OVMF:
+```
+FS0:\> ShowTables.efi
+EE4E5898-3914-4259-9D6E-DC7BD79403CF, 78EDF98
+05AD34BA-6F02-4214-952E-4DA0398E2BB9, 7ED2AC0
+7739F24C-93D7-11D4-9A3A-0090273FC14D, 78EA018
+4C19049F-4137-4DD3-9C10-8B97A83FFDFA, 7ED3AA0
+49152E77-1ADA-4764-B7A2-7AFEFED95E8B, 7ED5F10
+060CC026-4C0D-4DDA-8F41-595FEF00A502, 7942018
+EB9D2D31-2D88-11D3-9A16-0090273FC14D, 7941000
+EB9D2D30-2D88-11D3-9A16-0090273FC14D, 7B7E000
+8868E871-E4F1-11D3-BC22-0080C73C8881, 7B7E014
+DCFA911D-26EB-469F-A220-38B7DC461220, 6E86018
+```
+
+_______
+
+Let's search edk2 codebase for GUIDs:
+```
+EE4E5898-3914-4259-9D6E-DC7BD79403CF, 78EDF98
+```
+`gLzmaCustomDecompressGuid`
+
+LZMA_CUSTOM_DECOMPRESS_GUID
+
+https://github.com/tianocore/edk2/tree/master/MdeModulePkg/Include/Guid/LzmaDecompress.h
+
+GUID indicates the LZMA custom compress/decompress algorithm.  
+The Global ID used to identify a section of an FFS file of type EFI_SECTION_GUID_DEFINED, whose contents have been compressed using LZMA. 
+```
+05AD34BA-6F02-4214-952E-4DA0398E2BB9, 7ED2AC0
+```
+`gEfiDxeServicesTableGuid`
+
+DXE_SERVICES_TABLE_GUID 
+
+https://github.com/tianocore/edk2/tree/master/MdePkg/Include/Guid/DxeServices.h (DXE Services Table)
+
+```
+7739F24C-93D7-11D4-9A3A-0090273FC14D, 78EA018
+```
+`gEfiHobListGuid`
+
+https://github.com/tianocore/edk2/tree/master/MdePkg/Include/Guid/HobList.h
+
+HOB List passed from PEI to DXE
+
+```
+4C19049F-4137-4DD3-9C10-8B97A83FFDFA, 7ED3AA0
+```
+`gEfiMemoryTypeInformationGuid` 
+
+https://github.com/tianocore/edk2/tree/master/MdeModulePkg/Include/Guid/MemoryTypeInformation.h
+
+The memory type information HOB
+
+```
+49152E77-1ADA-4764-B7A2-7AFEFED95E8B, 7ED5F10
+```
+
+`gEfiDebugImageInfoTableGuid`
+
+https://github.com/tianocore/edk2/tree/master/MdePkg/Include/Guid/Debug ImageInfoTable.h
+
+Debug Image Info Table
+
+```
+060CC026-4C0D-4DDA-8F41-595FEF00A502, 7942018
+```
+`gMemoryStatusCodeRecordGuid`
+
+https://github.com/tianocore/edk2/tree/master/MdeModulePkg/Include/Guid/MemoryStatusCodeRecord.h
+
+Status code records HOB that originate from the PEI status code
+
+```
+EB9D2D31-2D88-11D3-9A16-0090273FC14D, 7941000
+```
+`gEfiSmbiosTableGuid` 
+
+https://github.com/tianocore/edk2/tree/master/MdePkg/Include/Guid/SmBios.h
+
+SMBIOS tables
+
+```
+EB9D2D30-2D88-11D3-9A16-0090273FC14D, 7B7E000
+```
+
+`gEfiAcpi10TableGuid` 
+
+ACPI_10_TABLE_GUID     ACPI_TABLE_GUID
+
+https://github.com/tianocore/edk2/tree/master/MdePkg/Include/Guid/Acpi.h
+
+ACPI tables for old specifications
+
+```
+8868E871-E4F1-11D3-BC22-0080C73C8881, 7B7E014
+```
+gEfiAcpiTableGuid/gEfiAcpi20TableGuid
+
+EFI_ACPI_20_TABLE_GUID EFI_ACPI_TABLE_GUID
+
+https://github.com/tianocore/edk2/tree/master/MdePkg/Include/Guid/Acpi.h
+
+ACPI tables for modern specifications
+
+```
+DCFA911D-26EB-469F-A220-38B7DC461220, 6E77018
+```
+
+gEfiMemoryAttributesTableGuid
+
+https://github.com/tianocore/edk2/tree/master/MdePkg/Include/Guid/MemoryAttributesTable.h
+
+UEFI Memory Attributes Table [Defined in UEFI spec]
+
+
diff --git a/README.md b/README.md
index 3083e40..93047ce 100644
--- a/README.md
+++ b/README.md
@@ -28,6 +28,7 @@ Lessons description:
 - Lesson 23: PatchableInModule PCDs and how they can be changed via `GenPatchPcdTable`/`PatchPcdValue` utilities 
 - Lesson 24: Dynamic/DynamicEx PCDs
 - Lesson 25: More on PCDs
+- Lesson 26: Tables referenced in `EFI_CONFIGURATION_TABLE`
 
 ______