As you remember the entry point for our UEFI programs is:
EFI_STATUS
EFIAPI
UefiMain (
IN EFI_HANDLE ImageHandle,
IN EFI_SYSTEM_TABLE *SystemTable
)
The passed structure EFI_SYSTEM_TABLE looks like this according to UEFI specification:
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.
typedef struct{
EFI_GUID VendorGuid;
VOID *VendorTable;
} EFI_CONFIGURATION_TABLE;
Let's create a simple program ShowTables to look at tables referenced by this structure in 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]