Update U-Boot Bootargs
Update the U-Boot Arguments to Support Ultra-Fast Boot
Ultra-Fast Boot relies on the Linux®-based Suspend-to-RAM (STR) feature to capture a DRAM snapshot. The most common STR implementation is Microchip's Backup Mode with DDR Self-Refresh (BSR) mode, which requires 'BACKUP' mode support in the 'atmel.pm_modes' kernel parameter.
Low-Power Mode Support for Ultra-Fast Boot
Each Ultra-Fast Boot operating mode requires corresponding low-power mode support.
| Manual Save and Load | Auto Save and Load | Pre-Saved Load | |
|---|---|---|---|
| Low-Power Mode | BACKUP mode | RESTORE mode | SNAPSHOT mode |
Update Low-Power Mode in U-Boot
The bootargs variable is used as an exchange area to pass information to the main application started by U-Boot (Linux kernel, for instance).
Here are examples to update bootargs with BACKUP mode:
Update the U-Boot argument for BACKUP mode.
Boot the board with an SD card.
When U-Boot appears, press any key to stop autoboot.
Type "print" to print environment variables.
Update the bootargs variable with backup instead of ulp1.
Save updated variables with the saveenv command:
Continue to load the kernel.
Type “boot” to continue loading the kernel as shown in the accompanying image:
