Ubuntu 19.10 on the Raspberry Pi has /boot/firmware/README stating the following:
An overview of the files on the /boot/firmware partition (the 1st partition
on the SD card) used by the Ubuntu boot process (roughly in order) is as
follows:
* bootcode.bin - this is the second stage bootloader loaded by all pis with
the exception of the pi4 (where this is replaced by flash
memory)
* config.txt - the first configuration file read by the boot process
* syscfg.txt - the file in which system modified configuration will be
placed, included by config.txt
* usercfg.txt - the file in which user modified configuration should be
placed, included by config.txt
⋯
include syscfg.txt
include usercfg.txt
Also, /boot/firmware/config.txt has the following notice at the top:
# Please DO NOT modify this file; if you need to modify the boot config, the
# "usercfg.txt" file is the place to include user changes. Please refer to
# the README file for a description of the various configuration files on
# the boot partition.
However, any configuration directives placed in /boot/firmware/usercfg.txt, such as gpu_mem=16, are ignored on boot.
I am familiar with the use of /boot/config.txt under Raspbian, where all firmware configuration directives are placed in this single file, and the 'include' directive is not supported.
Ubuntu seems to have extended this mechanism, presumably through its use of uboot, by adding 'include' and splitting configuration into multiple files, but it just doesn't seem to work. I'm still having to add directives to the config.txt file for them to take effect.
Can anyone explain this?
