On 21/04/25 12:15, Peter Robinson wrote:
Hi Mauro,
We recently started using U-Boot on various Raspberry Pi 5 boards
with different hardware configurations.
While testing, Simon noticed unusual boot failures, such as the kernel
failing to boot with no output or U-Boot reporting:
"ERROR: Did not find a cmdline Flattened Device Tree."
Today, I spent time investigating these issues. It appears that U-Boot
retrieves several variables from the Raspberry Pi firmware, with fdt_addr
being particularly important.
If the environment is saved, fdt_addr gets stored and takes precedence
over what the firmware provides to U-Boot.
Interestingly, the RPi firmware seems to modify fdt_addr based on connected
hardware. Our experiments showed that even attaching an RPi camera module
changes the computed fdt_addr and U-Boot reads from the wrong memory location.
As a result, saving the environment, whether via the saveenv command in U-Boot
or fw_setenv in Linux, can lead to boot failures if the hardware configuration
changes.
Do you have any suggestions for mitigating this issue?
In my opinion, U-Boot should not override such critical variables.
Thanks,
//richard
Hi Richard,
could be related tho this [1]?
I sent this patch some years ago but was never accepted in u-boot tree.
But meta-rpi uses it in u-boot recipe [2].
After digging into this and a discussion with Tom we decided this is
the correct fix so I've pulled that patch in for 2025.07.
Thanks,
Peter
Hi Peter,
thank you.
Regards
Mauro
Regards
[1] https://lists.denx.de/pipermail/u-boot/2021-May/449609.html
[2]
https://github.com/agherzan/meta-raspberrypi/blob/master/recipes-bsp/u-boot/files/0001-rpi-always-set-fdt_addr-with-firmware-provided-FDT-address.patch
--
Mauro
