How to set u-boot environment variable
Hi all,
I've perused all u-boot documentation I could find, but nowhere I
found an answer to my (I think) fairly simple question:
Given a bootable SD card, how can I change u-boot's behavior to, for
example, load a different kernel image or use different environment
variables (I'm most desperate to set the device to have a fixed MAC
address)?
I think the environment variables need to be written to a specific
location on the SD card, but u-boot-tools provides no such tool. man
fw_setenv needs a file /etc/env.config, but my system (which is a
finished image I copied from somewhere) doesn't have that.
So, how is it done?
Below is a listing of the /boot partition of my SD card. My system, as
it is, boots the 3.8 kernel.
This begs some additional questions:
- Why is there a 3.10 System.map and not a 3.8 one? Is this file even needed?
- What's the difference between uImage and zImage, and why does one
kernel version have
a uImage and the other a zImage?
- Is the "dts" file the source that the "dtb" file was created from,
or does it have some
other purpose?
Thanks,
robert
root@odroid:/boot# ls -l
total 19876
-rw-r--r-- 1 root root 113039 Apr 25 2015 config-3.10.75-84
-rw-r--r-- 1 root root 102534 Mar 4 2015 config-3.8.13.30
-rw-r--r-- 1 root root 4216745 Dec 20 19:33 initrd.img-3.10.75-84
-rw-r--r-- 1 root root 18358 Apr 25 2015 meson8b_odroidc.dtb
-rw-r--r-- 1 root root 36941 Apr 25 2015 meson8b_odroidc.dts
-rw-r--r-- 1 root root 1910532 Apr 25 2015 System.map-3.10.75-84
-rw-r--r-- 1 root root 5468767 Apr 25 2015 uImage-3.10.75-84
-rw-r--r-- 1 root root 3949837 May 4 2015 uInitrd-3.10.75-84
-rw-r--r-- 1 root root 2157425 May 3 2015 uInitrd-3.8.13.30
-rw-r--r-- 1 root root 2352088 May 4 2015 zImage-3.8.13.30
root@odroid:/boot#
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