From cd2e740dde9541ad5f1d9efd93bcb5a967379ece Mon Sep 17 00:00:00 2001
From: Tuomas Tynkkynen <tuomas@tuxera.com>
Date: Wed, 24 Jan 2018 16:43:16 +0200
Subject: [PATCH] nixos/sd-image-aarch64.nix: Set avoid_warnings in RPi
 config.txt

Also add some comments on the existing config settings as well.
---
 nixos/modules/installer/cd-dvd/sd-image-aarch64.nix | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/nixos/modules/installer/cd-dvd/sd-image-aarch64.nix b/nixos/modules/installer/cd-dvd/sd-image-aarch64.nix
index efb9ba39bcd4..bc6dfb25e863 100644
--- a/nixos/modules/installer/cd-dvd/sd-image-aarch64.nix
+++ b/nixos/modules/installer/cd-dvd/sd-image-aarch64.nix
@@ -42,8 +42,17 @@ in
     populateBootCommands = let
       configTxt = pkgs.writeText "config.txt" ''
         kernel=u-boot-rpi3.bin
+
+        # Boot in 64-bit mode.
         arm_control=0x200
+
+        # U-Boot used to need this to work, regardless of whether UART is actually used or not.
+        # TODO: check when/if this can be removed.
         enable_uart=1
+
+        # Prevent the firmware from smashing the framebuffer setup done by the mainline kernel
+        # when attempting to show low-voltage or overtemperature warnings.
+        avoid_warnings=1
       '';
       in ''
         (cd ${pkgs.raspberrypifw}/share/raspberrypi/boot && cp bootcode.bin fixup*.dat start*.elf $NIX_BUILD_TOP/boot/)