Some new autoboot features
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#2 Some new autoboot features
This patch makes three changes that help in autoboot
scenarios.
1) When using CONFIG_ALTBOOTCOMMAND or
CONFIG_BOOTCOUNT_LIMIT, the corresponding environment
variable is set by default to the value of that #define.
2) A new option is available to make U-Boot not have a
console: CONFIG_NON_INTERACTIVE.
3) When using CONFIG_BOOTDELAY, one may use
CONFIG_BOOTCOMMAND_SELECT instead of
CONFIG_BOOTCOMMAND. When used, U-Boot selects one of
two autoboot commands by checking a byte in memory to
figure out which one to use. The value of
CONFIG_BOOTCOMMAND_SELECT is used as the address of the
byte to read. If the byte is 0, the enviroment variable
"bootcmd0" is used as the autoboot command. If the byte
is non-zero, "bootcmd1" is used. Their default values
are set to CONFIG_BOOTCOMMAND0 and CONFIG_BOOTCOMMAND1
if defined.
This option allows systems that must auto-boot to be
able to safely upgrade their boot image. By having two
areas for an image in flash and using a specific byte
in an isolated sector to select between them, one can
overwrite the image that is not in use and then
reprogram the sector with the selection byte. As a
result, at no point in the process will a power failure
render the system inoperable.
A patch for u-boot 1.1.4 to add the described features. Apply as "patch -p1 < u-boot-1.1.4-extra-autoboot-features.patch"