From a9cc56e31565902f745f0bcd77a560966536b4c5 Mon Sep 17 00:00:00 2001
From: Mathias Beaulieu-Duncan <mathias@openharbor.io>
Date: Mon, 16 Feb 2026 18:45:05 -0500
Subject: [PATCH] Fix PCIe Gen 3: move dtparam into [pi5] section of config.txt

The dtparam=pciex1_gen=3 was being appended after the [all] section,
but RPi firmware requires PCIe dtparams in the [pi5] section.
Switch from configTxtAppend to full configTxt replacement to control
section ordering. Also add dtparam=pciex1 to explicitly enable the
external PCIe link.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
---
 Makefile                 |  2 +-
 config/config.txt        | 31 +++++++++++++++++++++++++++++++
 config/config.txt.append |  3 ++-
 3 files changed, 34 insertions(+), 2 deletions(-)
 create mode 100644 config/config.txt

diff --git a/Makefile b/Makefile
index de7e630..7cc4988 100644
--- a/Makefile
+++ b/Makefile
@@ -57,7 +57,7 @@ ATTESTATION_ARGS = --provenance=mode=max --sbom=true
 IMAGER_COMMON_FLAGS = \
 	--overlay-name="rpi5" \
 	--overlay-image="$(OVERLAY_IMAGE):$(SBCOVERLAY_TAG)" \
-	--overlay-option="configTxtAppend=$$(cat $(PWD)/config/config.txt.append)" \
+	--overlay-option="configTxt=$$(cat $(PWD)/config/config.txt)" \
 	$(EXTENSION_FLAGS)
 
 #
diff --git a/config/config.txt b/config/config.txt
new file mode 100644
index 0000000..7c873d2
--- /dev/null
+++ b/config/config.txt
@@ -0,0 +1,31 @@
+# See https://www.raspberrypi.com/documentation/computers/configuration.html
+# Reduce GPU memory to give more to CPU.
+gpu_mem=32
+# Enable maximum compatibility on both HDMI ports;
+# only the one closest to the power/USB-C port will work in practice.
+hdmi_safe:0=1
+hdmi_safe:1=1
+# Load U-Boot.
+kernel=u-boot.bin
+# Forces the kernel loading system to assume a 64-bit kernel.
+arm_64bit=1
+# Run as fast as firmware / board allows.
+arm_boost=1
+# Enable the primary/console UART (globally).
+enable_uart=1
+# Disable UART on Pi5 to avoid U-Boot compatibility issue.
+# The debug UART (ttyAMA10) is always active regardless of this setting.
+[pi5]
+enable_uart=0
+# Enable PCIe and force Gen 3 for NVMe (~800 MB/s vs ~400 MB/s Gen 2)
+dtparam=pciex1
+dtparam=pciex1_gen=3
+[all]
+# Disable Bluetooth.
+dtoverlay=disable-bt
+# Disable Wireless Lan.
+dtoverlay=disable-wifi
+# CM5 Overclock — 2.6GHz stable on Compute Blade with heatsink
+arm_freq=2600
+over_voltage_delta=50000
+arm_boost=1
diff --git a/config/config.txt.append b/config/config.txt.append
index 6769e00..3d01f0a 100644
--- a/config/config.txt.append
+++ b/config/config.txt.append
@@ -3,5 +3,6 @@ arm_freq=2600
 over_voltage_delta=50000
 arm_boost=1
 
-# Enable PCIe Gen 3 for NVMe (~800 MB/s vs ~400 MB/s Gen 2)
+# Enable external PCIe link and set Gen 3 for NVMe (~800 MB/s vs ~400 MB/s Gen 2)
+dtparam=pciex1
 dtparam=pciex1_gen=3