Category: Riotboard

U-Boot fw_env.config for Riotboard

For all you U-Boot users out there, if you set bootdelay=0 on a Riotboard, you will have problems if you ever want to get back into the U-Boot configuration menu.

To erase or modify the U-Boot environment settings, you need to create an /etc/fw_env.config that the U-Boot userspace tools can use.

tl;dr

This is what the fw_env.config file should look like on a Riotboard (at least, when using a build of Freescale’s General Availability kernels):

# Device        Env. Offset   Env. Size    Flash Sector Size
/dev/mmcblk3    0x60000       0x2000       0x1000

The U-Boot environment is saved to /dev/mmcblk3, which is tricky, because the partition table explicitly defines an unused area at the beginning of the eMMC storage device.

Once you’ve got the configuration file in place, running fw_printenv should show something like:

# fw_printenv
baudrate=115200
boot_a_script=load ${devtype} ${devnum}:${bootpart} ${scriptaddr} ${prefix}${script}; source ${scriptaddr}
boot_extlinux=sysboot ${devtype} ${devnum}:${bootpart} any ${scriptaddr} ${prefix}extlinux/extlinux.conf
boot_prefixes=/ /boot/
boot_script_dhcp=boot.scr.uimg
boot_scripts=boot.scr.uimg boot.scr
boot_targets=mmc0 mmc1 mmc2 usb0 pxe dhcp 
bootcmd=run distro_bootcmd
bootcmd_dhcp=usb start; if dhcp ${scriptaddr} ${boot_script_dhcp}; then source ${scriptaddr}; fi
bootcmd_mmc0=setenv devnum 0; run mmc_boot
bootcmd_mmc1=setenv devnum 1; run mmc_boot
bootcmd_mmc2=setenv devnum 2; run mmc_boot
bootcmd_pxe=usb start; dhcp; if pxe get; then pxe boot; fi
bootcmd_usb0=setenv devnum 0; run usb_boot
bootdelay=0
bootm_size=0x10000000
distro_bootcmd=for target in ${boot_targets}; do run bootcmd_${target}; done
ethact=FEC
ethprime=FEC
fdt_addr_r=0x13000000
fdtfile=imx6dl-riotboard.dtb
kernel_addr_r=0x12000000
loadaddr=0x12000000
mmc_boot=if mmc dev ${devnum}; then setenv devtype mmc; run scan_dev_for_boot_part; fi
pxefile_addr_r=0x13200000
ramdisk_addr_r=0x13300000
scan_dev_for_boot=echo Scanning ${devtype} ${devnum}:${bootpart}...; for prefix in ${boot_prefixes}; do run scan_dev_for_extlinux; run scan_dev_for_scripts; done
scan_dev_for_boot_part=part list ${devtype} ${devnum} -bootable devplist; env exists devplist || setenv devplist 1; for bootpart in ${devplist}; do if fstype ${devtype} ${devnum}:${bootpart} bootfstype; then rune
scan_dev_for_extlinux=if test -e ${devtype} ${devnum}:${bootpart} ${prefix}extlinux/extlinux.conf; then echo Found ${prefix}extlinux/extlinux.conf; run boot_extlinux; echo SCRIPT FAILED: continuing...; fi
scan_dev_for_scripts=for script in ${boot_scripts}; do if test -e ${devtype} ${devnum}:${bootpart} ${prefix}${script}; then echo Found U-Boot script ${prefix}${script}; run boot_a_script; echo SCRIPT FAILED: cone
scriptaddr=0x13100000
stderr=serial
stdin=serial
stdout=serial
usb_boot=usb start; if usb dev ${devnum}; then setenv devtype usb; run scan_dev_for_boot_part; fi

You can now use the fw_setenv command to reset the bootdelay parameter.

Figuring Out The Right Configuration Parameters

If you’re using the U-Boot riotboard_defconfig, you’ll see:

#define CONFIG_SYS_EXTRA_OPTIONS "IMX_CONFIG=board/boundary/nitrogen6x/nitrogen6s1g.cfg,MX6S,DDR_MB=1024,ENV_IS_IN_MMC"

If you then look at include/configs/embestmx6boards.h, you’ll see the configuration used to store the environment:

/* Environment organization */
#define CONFIG_ENV_SIZE			(8 * 1024)

#if defined(CONFIG_ENV_IS_IN_MMC)
/* RiOTboard */
#define CONFIG_FDTFILE	"imx6dl-riotboard.dtb"
#define CONFIG_SYS_FSL_USDHC_NUM	3
#define CONFIG_SYS_MMC_ENV_DEV		2	/* SDHC4 */
#define CONFIG_ENV_OFFSET		(6 * 64 * 1024)
#define CONFIG_SUPPORT_EMMC_BOOT /* eMMC specific */
#elif defined(CONFIG_ENV_IS_IN_SPI_FLASH)
...
#endif

Kind of a pain in the ass that no one at embest thought it would be useful to document this information.