2025-05-04 20:57:23 +03:00
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# FVP Base platform overview
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### Boot sequence
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FVP Base emulator is typically launched using both a secure flashloader and
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a normal flashloader. The configuration looks like this:
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```shell
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-C bp.secureflashloader.fname=path/to/arm-trusted-firmware/build/fvp/debug/bl1.bin \
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2025-05-05 02:45:08 +03:00
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-C bp.flashloader0.fname=path/to/fip.bin
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2025-05-04 20:57:23 +03:00
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```
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We use Arm Trusted Firmware (ATF) as the secure monitor running at S-EL3. It
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initializes the system, sets up the secure world, and pass control to the
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non-secure world.
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#### The boot sequence works in the following way:
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- BL1 (Secure ROM Bootloader) - Initializes trusted components and loads the
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next stage (BL2).
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- BL2 (Trusted Boot Firmware) - Verifies and loads the next stages: BL31 and
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BL33.
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- BL31 (EL3 Runtime Firmware) - Provides runtime services at EL3, including
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PSCI (Power State Coordination Interface) and context switching between
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secure and non-secure worlds.
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- BL32 (Secure Payload) - optional secure-world component that runs at S-EL1.
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It is used to provide Trusted Execution Environment (TEE). If not required,
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this stage can be skipped, and BL31 will directly pass control to BL33. In our
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case we do not use BL32.
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- BL33 (Non-secure Payload) - The final stage of the boot chain, typically the
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entry point to the non-secure kernel or bootloader. We use little kernel as
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BL33.
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#### Memory Usage (bytes) [RAM]
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| Component | Start | Limit | Size | Free | Total |
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|-----------|-----------|-----------|---------|---------|--------|
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| BL1 | 0x4034000 | 0x4040000 | 0x7000 | 0x5000 | 0xc000 |
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| BL2 | 0x4020000 | 0x4034000 | 0x10000 | 0x4000 | 0x14000|
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| BL2U | 0x4020000 | 0x4034000 | 0xa000 | 0xa000 | 0x14000|
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| BL31 | 0x4003000 | 0x4040000 | 0x22000 | 0x1b000 | 0x3d000|
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#### Memory Usage (bytes) [ROM]
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| Component | Start | Limit | Size | Free | Total |
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|-----------|-----------|-----------|---------|-----------|----------|
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| BL1 | 0x0000000 | 0x4000000 | 0x8bd0 | 0x3ff7430 | 0x4000000|
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To check the memory layout, refer to [TF-A Memory Layout Tool
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Documentation](https://trustedfirmware-a.readthedocs.io/en/latest/tools/memory-layout-tool.html)
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#### Little kernel and DTB location
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On the FVP platform, DTB start address and the BL33 entry point are both
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configured in the platform’s source files:
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- **DTB base address**: `0x82000000 (32MB size)`
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- **BL33 entry address**: `0x88000000`
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You can find these settings in the `platform_def.h` header file:
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- [DTB
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address](https://github.com/ARM-software/arm-trusted-firmware/blob/v2.12.0/plat/arm/board/fvp/include/platform_def.h#L94-L100)
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- [BL33 entry
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address](https://github.com/ARM-software/arm-trusted-firmware/blob/v2.12.0/plat/arm/board/fvp/include/platform_def.h#L143)
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DTS for FVP Base you can find at [fdts](
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https://github.com/ARM-software/arm-trusted-firmware/tree/v2.12.0/fdts)
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### Peripheral Address Map
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The peripheral address map for the FVP Base platform can be found in the following documentation:
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[Base Platform memory map](https://developer.arm.com/documentation/100964/latest/Base-Platform/Base-Platform-memory/Base-Platform-memory-map?lang=en)
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Currently, little kernel supports:
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- **UART0,PL011**
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- **GICv2**
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### Interrupt Assignment
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The interrupt assignment for the FVP Base platform can be found in the following documentation:
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2025-05-05 02:45:08 +03:00
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[Base Platform interrupt assignments](https://developer.arm.com/documentation/100964/1128/Base-Platform/Base-Platform-interrupt-assignments?lang=en)
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