https://github.com/technical-writer-ssr/boot-process
Documentation for the boot process of i.MX, ARM Linux, and Android boards.
https://github.com/technical-writer-ssr/boot-process
android arm arm64 boot builtin flow imx nxp-cortex processing
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Documentation for the boot process of i.MX, ARM Linux, and Android boards.
- Host: GitHub
- URL: https://github.com/technical-writer-ssr/boot-process
- Owner: Technical-Writer-SSR
- Created: 2025-12-15T06:46:46.000Z (6 months ago)
- Default Branch: main
- Last Pushed: 2025-12-15T06:51:19.000Z (6 months ago)
- Last Synced: 2025-12-18T03:50:24.555Z (6 months ago)
- Topics: android, arm, arm64, boot, builtin, flow, imx, nxp-cortex, processing
- Homepage:
- Size: 118 KB
- Stars: 2
- Watchers: 0
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
# Boot Process
## Overview
This document details the boot process for NXP ARM-based development boards running Linux and Android operating systems. The boot sequence follows a multi-stage architecture from power-on to full OS initialization.
## Boot Process Architecture
```mermaid
graph TD
A[Power On/Reset] --> B[Boot ROM
On-Chip ROM];
B --> C{Boot Mode Selection
eMMC/SD/USB/UART};
subgraph "i.MX 8 Series"
C --> D1[i.MX 8 Boot Flow];
D1 --> E1[SCFW → SPL → ATF];
E1 --> F1[U-Boot → Linux/Android];
end
subgraph "i.MX 6/7 Series"
C --> D2[i.MX 6/7 Boot Flow];
D2 --> E2[DCD → SPL → U-Boot];
E2 --> F2[Linux Kernel];
end
subgraph "Layerscape Series"
C --> D3[Layerscape Boot Flow];
D3 --> E3[RCW → U-Boot → PPA];
E3 --> F3[Linux/DPDK];
end
subgraph "Kinetis Series"
C --> D4[Kinetis Boot Flow];
D4 --> E4[XIP/MCUBoot];
E4 --> F4[RTOS/Embedded];
end
F1 --> G[Device Tree Init];
F2 --> G;
F3 --> G;
F4 --> G;
G --> H[Kernel Initialization];
H --> I[Init Process];
I --> J[Userspace];
style A fill:#f9f,stroke:#333,stroke-width:2px
style J fill:#ccf,stroke:#333,stroke-width:2px
style D1 fill:#d4f7d4
style D2 fill:#d4e6f7
style D3 fill:#f7d4e6
style D4 fill:#f7f2d4
```
## Board-Specific Boot Flows
### 1. **i.MX 8 Series (i.MX 8M/8M Mini/8M Plus/8QM)**
```mermaid
graph LR
A[Boot ROM] --> B[Load SCFW
System Controller];
B --> C[SCFW loads SPL];
C --> D[SPL loads ATF
ARM Trusted Firmware];
D --> E[ATF loads U-Boot];
E --> F{U-Boot Actions};
F --> G[Load DTB];
F --> H[Load Kernel];
F --> I[AVB Verification];
G & H & I --> J[Boot Linux/Android];
```
**Key Components:**
- **SCFW**: System Controller Firmware (manages power, clocks, security)
- **ATF**: ARM Trusted Firmware (EL3 secure monitor)
- **OPTEE**: Optional TEE for secure applications
- **AVB**: Android Verified Boot (for Android images)
**Typical Boards:** i.MX 8M EVK, i.MX 8M Mini EVK, i.MX 8M Plus EVK
### 2. **i.MX 6/7 Series (i.MX 6Quad/6Dual/6Solo/7Dual)**
```mermaid
graph LR
A[Boot ROM] --> B[Read DCD
Device Config Data];
B --> C[Initialize DDR];
C --> D[Load SPL
Secondary Program Loader];
D --> E[SPL loads U-Boot];
E --> F{U-Boot Phase};
F --> G[Setup Board];
F --> H[Load Kernel];
F --> I[Load DTB];
G & H & I --> J[Boot Linux];
```
**Key Components:**
- **DCD**: Device Configuration Data (DDR timing parameters)
- **IVT**: Image Vector Table (image header structure)
- **HAB**: High Assurance Boot (security enforcement)
**Typical Boards:** Sabre SD, Sabre AI, i.MX 7Dual SABRE
### 3. **Layerscape Series (LX2160A, LS1046A, LS1028A)**
```mermaid
graph LR
A[Power On] --> B[Load RCW
Reset Configuration Word];
B --> C[Initialize SerDes];
C --> D[Load U-Boot];
D --> E[Load PPA
Platform Partition];
E --> F[Setup DPC
DPAA2 Complex];
F --> G[Load Linux/DPDK];
G --> H[Run Applications];
```
**Key Components:**
- **RCW**: Reset Configuration Word (pin multiplexing, SerDes config)
- **PPA**: Platform Partition Architecture (firmware partition)
- **DPAA2**: Data Path Acceleration Architecture
**Typical Boards:** Layerscape LX2160ARDB, LS1046ARDB, LS1028ARDB
### 4. **Kinetis Series (K64, K66, K28)**
```mermaid
graph LR
A[Reset] --> B[Boot ROM];
B --> C{Flash Type};
C --> D[XIP Execution];
C --> E[Load to RAM];
D & E --> F[MCUBoot
Optional];
F --> G[RTOS/Embedded App];
G --> H[Run Application];
```
**Key Components:**
- **XIP**: Execute-In-Place (run directly from flash)
- **MCUBoot**: Secure bootloader for MCUs
- **FlexSPI**: External flash interface
**Typical Boards:** FRDM-K64F, FRDM-K66F, TWR-K28F
## Common Boot Components
### Boot Media Options
| Media Type | Typical Use | Speed | Capacity |
|------------|-------------|-------|----------|
| eMMC | Primary storage | High | 4GB-64GB |
| SD Card | Development | Medium | Up to 512GB |
| QSPI Flash | Boot device | Medium | 16MB-256MB |
| NAND Flash | Cost-sensitive | Medium | 256MB-2GB |
| USB | Recovery/Download | Variable | N/A |
### Security Features
- **HAB** (High Assurance Boot): Code signing and verification
- **CAAM** (Cryptographic Accelerator): Hardware crypto engine
- **TrustZone**: ARM security extension
- **AVB 2.0**: Android Verified Boot
- **Secure JTAG**: Debug port protection
### Boot Configuration
```bash
# Typical U-Boot environment variables
bootcmd=mmc dev ${mmcdev}; mmc read ${loadaddr} ${kernel_addr} ${kernel_size}; \
mmc read ${fdt_addr} ${fdt_addr_r} ${fdt_size}; \
bootz ${loadaddr} - ${fdt_addr}
bootargs=console=ttymxc0,115200 root=/dev/mmcblk1p2 rootwait rw
```
## Quick Reference
### Boot Mode Selection
| Boot Pins | Mode | Description |
|-----------|------|-------------|
| 0000 | Serial Downloader | USB/UART recovery |
| 0001 | Internal Boot | Normal boot from flash |
| 0010 | USB Boot | Boot from USB device |
| 0100 | SD Card | Boot from SD/MMC |
### Common Commands
```bash
# U-Boot commands for i.MX
=> mmc list # List MMC devices
=> fatls mmc 0:1 # List files on FAT partition
=> boot # Boot with default settings
=> run netboot # Network boot
=> fastboot # Enter fastboot mode
```
## Troubleshooting
### Common Issues
1. **Boot hangs at SPL**: Check DDR initialization parameters
2. **HAB authentication fails**: Verify image signing
3. **Kernel panic early**: Check device tree compatibility
4. **No boot media detected**: Verify boot mode pins
### Debug Tools
- **UUU (Universal Update Utility)**: Flashing and recovery
- **OpenOCD**: JTAG debugging
- **U-Boot console**: Serial debug at 115200 baud
- **Linux dmesg**: Kernel boot messages
## Resources
- [NXP Official Documentation](https://www.nxp.com)
- [i.MX Linux Reference Manual](https://www.nxp.com/docs/en/user-guide/IMX_LINUX_USERS_GUIDE.pdf)
- [U-Boot Documentation](https://www.denx.de/wiki/U-Boot/Documentation)
- [ARM Trusted Firmware](https://trustedfirmware.org/)
## License
This documentation is provided for reference purposes. Refer to NXP official documentation for production use.
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*Last Updated: *
*For NXP i.MX, Layerscape, and Kinetis Platforms*