Create New Payload
Before you decide to support a new payload in SBL, it is recommended to check whether the existing payloads can be updated to support the new requirement.
For tightly-coupled payload, two steps are required to integrate a new payload:
Create a new payload starts with adding a new module in
PayloadPkg/<payload_bar>with entry point function
See Package Dependency when you are implementing payload code.
Build and integrate the new payload
The image size and memory location of the new payload can be configured in
BoardConfig.py. The following values are used in Apollo Lake platform payload configurations:
PAYLOAD_SIZE = 0x0001F000 EPAYLOAD_SIZE = 0x00120000 LOADER_RSVD_MEM_SIZE = 0x00B8C000 PLD_RSVD_MEM_SIZE = 0x00500000 PAYLOAD_LOAD_HIGH = 1
For loosely-coupled payload, you are full control of payload design and implementation.
For example, UEFI Payload is loosely-coupled payload.
SBL provides a HelloWorld payload example to illustrate how to write a very simple payload.
To build the HelloWorld payload, run the following command from SBL source tree:
python BuildLoader.py build_dsc -p PayloadPkg\PayloadPkg.dsc
The generated payload binary will be located at:
The path might change a little bit if using different toolchain or build options.
To use HelloWorld payload as the default payload instead of the OsLoader on QEMU platform, build SBL with the following command:
copy Build\PayloadPkg\DEBUG_VS2019\IA32\HelloWorld.efi PayloadPkg\PayloadBins /y python BuildLoader.py build qemu -p HelloWorld.efi:HLWD:Lz4
This generated SlimBootloader.bin will boot into HelloWorld payload on QEMU platform.
To add HelloWorld payload as additional paylaod, build SBL with the following command:
copy Build\PayloadPkg\DEBUG_VS2019\IA32\HelloWorld.efi PayloadPkg\PayloadBins /y python BuildLoader.py build qemu -p OsLoader.efi:LLDR:Lz4;HelloWorld.efi:HLWD:Lz4
The generated SlimBootloader.bin will boot into OsLoader or HelloWorld payload on QEMU platform depends on the GEN_CFG_DATA.PayloadId value at build time and runtime.
GEN_CFG_DATA.PayloadId can be customized in board CFGDATA DLT file. The PayloadId can be updated by SBL at runtime code by SetPayloadId() function.
Please refer to Integrate Multiple Payloads for multiple payloads support.