U-Boot environment
From Openmoko
The bootloader environment configures the bootloader. Between reboots, the environment is stored with a checksum in the internal flash partition called "u-boot_env". On the bootloader console, there are bootloader commands for environment manipulation.
Typical environment
baudrate=115200 bootargs=rootfstype=jffs2 root=/dev/mtdblock4 console=ttySAC0,115200 console=tty0 loglevel=8 dyntick=enable lpj=252416 usbtty=cdc_acm bootdelay=10 stdout=serial stderr=serial stdin=serial mtdparts=mtdparts=neo1973-nand:0x00030000(u-boot),0x0000c000(u-boot_env),0x00200000(kernel),0x00130000(splash),0x03c94000(rootfs) mtdids=nand0=neo1973-nand bootargs_base=rootfstype=jffs2 root=/dev/mtdblock4 console=ttySAC0,115200 console=tty0 loglevel=8 dyntick=enable lpj=252416 bootcmd=setenv bootargs ${bootargs_base} ${mtdparts}; nand read.e 0x32000000 kernel; bootm 0x32000000 pcf50606_int1=0x40 filesize=160C000 partition=nand0,0 mtddevnum=0 mtddevname=u-boot
Timeouts
If the boot loader menu is on the screen, the phone will power off when there hasn't been activity for a while. This is not nice if you are working on the boot loader console, but you can make the time longer:
setenv boot_menu_timeout [seconds]
After the phone is powered on, there is a short period of time when you can connect to the console and cancel the automatic boot without going to the menu:
setenv bootdelay [seconds]