Set system system.kernel ... cmdline not working?

device
1

$ sudo snap set system system.kernel.dangerous-cmdline-append=“dtparam=i2c_csi_dsi0”

$ sudo cat /proc/cmdline

reboot=w coherent_pool=1M 8250.nr_uarts=1 pci=pcie_bus_safe bcm2708_fb.fbwidth=640 bcm2708_fb.fbheight=480 bcm2708_fb.fbdepth=16 bcm2708_fb.fbswap=1 smsc95xx.macaddr=2C:CF:67:FC:A4:EA vc_mem.mem_base=0x3fc00000 vc_mem.mem_size=0x40000000 console=ttyAMA0,115200 dwc_otg.lpm_enable=0 console=tty1 rng_core.default_quality=700 vt.handoff=2 quiet splash snapd_recovery_mode=run

Ineffective? Just ignores it?

$ sudo snap set system system.kernel.cmdline-append=“dtparam=i2c_csi_dsi0”

error: cannot perform the following tasks:

  • Run configure hook of “core” snap (run hook “configure”: “dtparam=i2c_csi_dsi0” is not allowed in the kernel command line by the gadget)

fails?

I am trying to set a kernel parameter using both of the commands above yet both fail?

P.S. Ubuntu Core 24 running on CM5

2

As the docs state, “on devices using the GRUB bootloader”, RPI doesn’t use grub, so it doesn’t work.

You can edit the cmdline.txt directly, should be at /boot/piboot/. The snap set method is for systems where FDE is used to not break the integrity of TPM.

3

Huh……so you are saying cmdline.txt is not a read only file. I will try that. Thank you.

4

Beyond the hint that @gairepravesh gave already, are you aware that the kernel only adds changes to /proc/cmdline after you rebooted ? You wont see any immediate changes on the running system…

5

None of these appear to work for me. Even if i edit the cmdline.txt directly under /boot/pi-kernel*/cmdline.txt and add dtparam settings after a reboot they do not take effect. I have been reading that the only way to change device tree settings is to build your own pi-gadget snap and create your own model assertion for ubuntu core and burn that image ? Thats a lot of work just to change dtparam settings. To date what i have been doing is editing the config.txt but I can only reach this file by booting up my CM5 into USB (e.g. rpiboot) mode and actually editing the config.txt. This is cumbersome and I was hoping to change this.

6

Sorry, I didn’t actually realize the dtparam and just considered the problem statement to be adding cmdline params. Just for record, editing /boot/piboot/.snap/cmdline.txt is the correct way for editing cmdline in RPI. Its just that dtb’s are handled from config.txt by firmware so its not a valid arg for cmdline.

This was discussed here previously and a product feedback was created. I am not completely sure what’s the status of this as of now.

1 Like