Load Pre-saved Snapshot Image Mode

Introduction

Use this mode to boot quickly from a snapshot image that has already been prepared. In this mode, at91bootstrap does not save a new memory snapshot during the boot flow; instead, it loads a pre-saved snapshot image.

Previously, when the system entered a suspended state, raw data from the Dynamic Random-Access Memory (DRAM) context was captured via the JTAG interface. Subsequently, the memmap tool processed this data to generate the final snapshot image.

The generated snapshot image can be programmed using SAM-BA® In-System Programmer (ISP).

How It Works

Save State

After the system enters a suspended state, the user manually captures the raw DRAM context through the JTAG interface. The raw data is then converted into a final snapshot image using the memmap tools.

Restoring State

On the next boot, the system restores the saved snapshot instead of performing a full reload, significantly reducing startup time. The same snapshot continues to load at every startup until it is manually updated.

Applicable Scenarios

This mode involves loading a pre-generated snapshot image directly from flash memory, bypassing the need to save or generate a snapshot during shutdown. It is especially useful in scenarios where the system's state is known and static, such as in manufacturing or deployment environments where a consistent, tested system image is used for multiple devices.

Additionally, this mode is the only one compatible with the SAM9X60 and SAM9X7.

Supported Devices and Prerequisites

• Supported devices
  • SAMA5D2
  • SAMA7G54
  • SAMA7D65
  • SAM9X60 and SAM9X7
• Hardware requirements
  • PMIC is not necessary
  • JTAG interface
• Software requirements
  • PM mode support: snapshot mode (new)
  • Linux^® patch: fastboot-linux-based-on-linux4microchip-20XX.XX.patch
  • memmap tools: Offline Snapshot Generation

Creating a Snapshot Image in Load Pre-saved Snapshot Image Mode

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