# How to make a simple unikernel on RBPi

File required on Raspberry Pi 5:
- bcm2712-rpi-5-b.dtb (https://github.com/raspberrypi/firmware/blob/master/boot/bcm2712-rpi-5-b.dtb)
- overlays/bcm2712d0.dtbo (https://github.com/raspberrypi/firmware/blob/master/boot/overlays/bcm2712d0.dtbo)
- config.txt

CPU used by Raspberry Pi 5: Cortex-A76
BCM2712 is the Broadcom chip used by Raspberry Pi 5

# Memory layout

Gilbraltar has a fairly precise memory layout. Here are the different zones
(heap, stacks, etc.).

| Base       | Size                 | Contents                   | Remarks |
|------------|----------------------|----------------------------|---------|
| 00000000   | 32 KByte             | ARM Trusted Firmware       | BL31    |
| 0006F000   | 4 KByte              | EL3 Stack                  |
| 00070000   | 2 KByte              | Exception vector table EL3 |
| ...
| 00080000   | max. 6 MByte         | Kernel image               |
|            | .init                | startup code               |
|            | .text                |                            |
|            | .rodata              |                            |
|            | .data                |                            |
|            | .bss                 |                            |
| ...
|            | Kernel stacks        |                            |
| 00280000   | 128 KByte            | for Core 0                 |
| 002A0000   | 128 KByte            | for Core 1                 |
| 002C0000   | 128 KByte            | for Core 2                 |
| 002E0000   | 128 KByte            | for Core 3                 |
| 00300000   |                      | End of stacks              |
|            | Exception stacks     |                            |
| 00300000   | 32 KByte             | for Core 0                 |
| 00308000   | 32 KByte             | for Core 1                 |
| 00310000   | 32 KByte             | for Core 2                 |
| 00318000   | 32 KByte             | for Core 3                 |
| 00320000   |                      | End of exception stacks    |
|            | IRQ stack            |                            |
| 00320000   | 32 KByte             | for Core 0                 |
| 00328000   | 32 KByte             | for Core 1                 |
| 00330000   | 32 KByte             | for Core 2                 |
| 00338000   | 32 KByte             | for Core 3                 |
| 00340000   |                      | End of IRQ stacks          |
|            | FIQ stack            |                            |
| 00340000   | 32 KByte             | for Core 0                 |
| 00348000   | 32 KByte             | for Core 1                 |
| 00350000   | 32 KByte             | for Core 2                 |
| 00358000   | 32 KByte             | for Core 3                 |
| 00360000   |                      | End of FIQ stacks          |
| 00500000   | 4 MByte              | Coherent region            |
| 00900000   |                      |                            |
| 1b000000   | 16 MByte             | Pager                      |
| 1c000000   |                      |                            |
| 40000000   |                      | Heap                       |
| ...
| 100000000  | 8192 MB              | Heap                       |
| 1000000000 | 16 MByte             | AXI peripherals            |