Thanks for the good description.It looks like I should try to build u-boot from scratch and install it on my board. This is an odroid-u2 which was never widely popular, and it's pretty old, and I'm really having a hard time understanding the instructions in doc/README-odroid. There's also the additional issue of some mystic cryptographic binaries directly from hardkernel that somehow circumvent the TrustZone mechanism.
I had hoped that it was somehow possible to figure out where the u-boot environment needs to be on the SD card, and then to just create a new one using mkimage and dd. Regards, robert On Thu, Dec 22, 2016 at 6:51 PM, Vagrant Cascadian <[email protected]> wrote: > On 2016-12-22, Robert Latest wrote: >> 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)? > > It's entirely platform-dependent. Some platforms have it located at a > raw offset on the boot media, some load a uenv.txt file, some load a > uboot.env file, etc... > > You can configure flash-kernel to generate a boot script which can set > variables in u-boot, if you platform supports loading a boot.scr. > > >> 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. > > The locations are board-specific. There are some examples for > /etc/fw_env.config in /usr/share/doc/u-boot-tools/examples/. > > I'd still suggest using a flash-kernel boot script instead, if you can, > as saving the environment variables means when you upgrade u-boot, you > don't benefit from new defaults if there are bugs fixed or improved > features in the default environment. > > >> - What's the difference between uImage and zImage, and why does one >> kernel version have a uImage and the other a zImage? > > uImage is a wrapper that includes some checksums to verify image > integrity. Many modern u-boot versions support loading the zImage file > directly with "bootz". > > >> - Is the "dts" file the source that the "dtb" file was created from, >> or does it have some other purpose? > > Hopefully the dts is the source... although you can generate the .dts > From the .dtb and compare to make sure... > > > Sounds like the image you're using is using vendor-built kernels and > presumably kernel trees, so the behavior of those may not be consistant > with a debian-provided kernel image. > > > live well, > vagrant
