fw_env_config

fw_env.config Configuration File- Legacy format

This is the configuration file for fw_{printenv,setenv} utility. It was defined in U-Boot project and it is defined here as legacy format.

Up to two entries are valid, in this case the redundant environment sector is assumed present. Notice, that the "Number of Sectors" is not required on NOR and SPI dataflash. Futhermore, if the Flash Sector Size is omitted, this value is assumed to be the same as the Environment Size, which is valid for NOR and SPI dataflash. Device Offset must be prefixed with 0x to be parsed as a hexadecimal value.

Structure of the Configuration File

Entries must be separated by spaces or tabs.

Device Name	Device Offset	Environment Size	Flash Sector Size	Number of Sectors	Disable Lock Mechanism

• Device Name: device or file where environment is stored (mandatory)
• Device Offset: offset from start of file or device (mandatory)
• Environment Size: size of environment (in bytes)
• Flash Sector Size: (optional) if not set, it is read from kernel
• Number of Sectors: (optional) number of sectors for environment (mainly used with raw NAND)
• Disable Lock Mechanism : (optional), 0|1, default=0 (LOCK enabled)

NOR Example

Device Name	Device Offset	Environment Size	Flash Sector Size	Number of Sectors	Disable Lock Mechanism
/dev/mtd1	0x0	0x4000	0x4000
/dev/mtd2	0x0	0x4000	0x4000

MTD SPI Dataflash Example

Device Name	Device Offset	Environment Size	Flash Sector Size	Number of Sectors	Disable Lock Mechanism
/dev/mtd5	0x4200	0x4000
/dev/mtd6	0x4200	0x4000

NAND Example

Device Name	Device Offset	Environment Size	Flash Sector Size	Number of Sectors	Disable Lock Mechanism
/dev/mtd0	0x4000	0x4000	0x20000	2

Block Device Example

On a block device a negative offset is treated as a backwards offset from the end of the device/partition, rather than a forwards offset from the start.

Device Name	Device Offset	Environment Size	Flash Sector Size	Number of Sectors	Disable Lock Mechanism
/dev/mmcblk0	0xC0000	0x20000
/dev/mmcblk0	-0x20000	0x20000

VFAT Example

Device Name	Device Offset	Environment Size	Flash Sector Size	Number of Sectors	Disable Lock Mechanism
/boot/uboot.env	0x0	0x4000

UBI Volume Example

Device Name	Device Offset	Environment Size	Flash Sector Size	Number of Sectors	Disable Lock Mechanism
/dev/ubi0_0	0x0	0x1f000	0x1f000
/dev/ubi0_1	0x0	0x1f000	0x1f000

UBI Volume by Name Example

Device Name	Device Offset	Environment Size	Flash Sector Size	Number of Sectors	Disable Lock Mechanism
/dev/ubi0:env	0x0	0x1f000	0x1f000
/dev/ubi0:redund	0x0	0x1f000	0x1f000

Configuration File in YAML

A YAML format is defined to allow multiple sets of variable. This lets have same features (redundancy, power-cut safe) for environment that are not bound to the U-Boot bootloader.

uboot:
  size : 0x4000
  lockfile : /var/lock/fw_printenv.lock
  devices:
    - path : /dev/mtd0
      offset : 0xA0000
      sectorsize : 0x10000
      unlock : yes
    - path : /dev/mtd0
      offset : 0xB0000
      sectorsize : 0x10000
      disable-lock : yes
 
appvar:
  size : 0x4000
  lockfile : /var/lock/appvar.lock
  devices:
    - path : /dev/mtd1
      offset : 0
      sectorsize : 0x10000
      unlock : yes
    - path : /dev/mtd1
      offset : 0x10000
      sectorsize : 0x10000