NixOS on ARM/Raspberry Pi 3: Difference between revisions
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If the Raspberry Pi downstream kernel is used the serial interface is named <code>serial0</code> instead. | If the Raspberry Pi downstream kernel is used the serial interface is named <code>serial0</code> instead. | ||
=== Early boot === | |||
Raspberry Pi 3's UART rate is tied to the GPU core frequency, set by default to 400MHz on Raspberry Pi 3 and later. This results in garbled serial output in bootloaders. Setting <code>core_freq=250</code> in <code>config.txt</code> solves this issue (as per [https://forums.raspberrypi.com/viewtopic.php?p=942203#p942203 thread on the Raspberry Pi forum]). | |||
It can be done declaratively as such: | |||
{{file|/etc/nixos/configuration.nix|nix|<nowiki> | |||
{ config, pkgs, lib, ... }: | |||
{ | |||
boot.loader.raspberryPi = { | |||
enable = true; | |||
version = 3; | |||
firmwareConfig = '' | |||
core_freq=250 | |||
''; | |||
}; | |||
} | |||
</nowiki>}} | |||
Note that this [https://github.com/RealVNC/raspi-documentation/blob/fc6b4711f91791db7acd19ae743fcfddc9c89546/configuration/config-txt/overclocking.md#overclocking-options may have a negative impact on performance]: | |||
<blockquote>Frequency of the GPU processor core in MHz. It has an impact on CPU performance because it drives the L2 cache and memory bus.</blockquote> | |||
== Bluetooth == | == Bluetooth == | ||