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Due to software requirements I'm running Debian Buster and am hoping to be able to give my Pi4 a slight overclock. I've created a confix.txt file in /boot with the following content:

over_voltage=2
arm_freq=1750

However, this doesn't appear to be having any affect. neofetch stil shows CPU: (4) @ 1.500GHz

and

lscpu | grep MHz

gives

CPU max MHz:         1500.0000
CPU min MHz:         600.0000

I don't seem to be able to find any references to overclocking a pi in Debian (buster) but several indicating that the above config.txt in /boot should be sufficient.

I've seen suggestions that /boot sometimes isn't the first partition that is read by the system on some OS' and that the Pi GPU takes the config.txt only from the first partition.

Any suggestions?

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  • Is over_voltage=over_voltage=2 a typing error? Overclock does not work if you have any power warnings raspberrypi.org/documentation/configuration/config-txt/… covers buster.
    – user115418
    Dec 19, 2020 at 17:03
  • @Andyroo No it wasn't. But, I've fixed that now and still no change after rebooting the system. Thanks. Dec 19, 2020 at 17:07
  • The overclocking from config.txt is the same regardless of OS because it is done before the OS is loaded and cannot be changed while the device is running.
    – goldilocks
    Dec 19, 2020 at 17:21
  • @goldilocks Ok, so then the questions remains, where this needs to be placed on a Debian Buster system since this the current location of /dev/boot/config.txt usn't having any effect. Therefore it seems that /dev/boot isn't the first partition being read by the GPU. Dec 19, 2020 at 17:52
  • Never seen anything other than /boot/config.txt read - Do you have the lines in a section not executed by the PI 4? Feel free to drop the whole of config.txt (minus lines starting with #) into a code block :-)
    – user115418
    Dec 19, 2020 at 18:10

1 Answer 1

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mount | grep boot give me this: /dev/mmcblk1p1 on /boot/firmware type vfat ...

The boot partition doesn't actually have to be mounted on the /boot directory when running1, and in fact it was probably a bad choice on behalf of Raspbian (the wisest choice IMO would have been a special dedicated subdirectory, eg. /boot/raspberry). Anyway, /dev/mmcblk0p1 is the partition you want, so if it is being mounted on /boot/firmware, the you should regard /boot/firmware as synonymous with Raspbian centric discussions of /boot. That's where your original config.txt would be (although it actually need not exist), and/or where you should put one if you want it to be applied.

Chances are you will see a listing corresponding to this in /etc/fstab.


  1. As mentioned in a previous comment the first partition doesn't need to be mounted at all, except for updating the contents and configuration there. Although the kernel image is stored and loaded from there, nothing in it is used by the OS.

    On actual Raspbian/RpiOS you should keep it as /boot and leave it mounted, since apt updates the firmware and kernel in it.

1
  • Yes, /boot/firmware is the effective "boot" partition Jan 6, 2021 at 14:43

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