From ae74be73d2c793b0847569d6c2993717ea9ec6b8 Mon Sep 17 00:00:00 2001
From: Stuart Hannon <stuartmhannon@gmail.com>
Date: Wed, 8 Jul 2026 12:34:17 -0400
Subject: [PATCH] Fix LINUX_OUT defaults to prevent parallel kernel
 cross-contamination
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Both build-kernel-mainline.sh and build-kernel-bsp.sh defaulted to
LINUX_OUT=prebuilt/linux. Running them in parallel (even with
--no-kernel on one) corrupted each other's output since both wrote
to the same directory.

Change the defaults to distinct paths:
  build-kernel-mainline.sh  → prebuilt/linux-mainline
  build-kernel-bsp.sh       → prebuilt/linux-bsp

Update README to reflect that parallel runs are now safe.

Closes #79.
---
 README.md                | 2 +-
 build-kernel-bsp.sh      | 2 +-
 build-kernel-mainline.sh | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/README.md b/README.md
index a8b70685..bbd9c9a9 100644
--- a/README.md
+++ b/README.md
@@ -226,7 +226,7 @@ Once you have bootloader outputs in `prebuilt/u-boot/` and kernel outputs in `pr
 
 This produces compressed images for each board whose bootloader is present. The kernel and root filesystem are shared; only the bootloader partition differs per board. Output files: `out/debian-<sector-size>-<board>-<timestamp>.img.gz` with a matching `.bmap` file, for both 512-byte and 4096-byte sector variants. When run inside the container, images go to `out/images/` instead (the container sets `IMG_OUT=/artifacts/images`).
 
-Don't run the mainline and BSP kernel scripts in parallel against the same output directory — both write to the same `prebuilt/linux/` path and the final packaging step will fail. Run one, then the other (or set separate `LINUX_OUT` paths).
+The mainline and BSP kernel scripts now default to separate output directories (`prebuilt/linux-mainline` and `prebuilt/linux-bsp`), so they can safely be run in parallel. If you need a custom path, set `LINUX_OUT` in the environment.
 
 ### Writing the image to SD/eMMC
 
diff --git a/build-kernel-bsp.sh b/build-kernel-bsp.sh
index 6f60141e..5f81678e 100755
--- a/build-kernel-bsp.sh
+++ b/build-kernel-bsp.sh
@@ -3,7 +3,7 @@
 : "${VENDOR_DTS:=vendor-dts}"
 : "${PATCHES_DIR:=patches/bsp}"
 : "${KEEP_SRC:=no}"
-: "${LINUX_OUT:=prebuilt/linux}"
+: "${LINUX_OUT:=prebuilt/linux-bsp}"
 : "${CROSS_COMPILE:=aarch64-linux-gnu-}"
 : "${CONFIGS:=configs/linux-bsp}"
 
diff --git a/build-kernel-mainline.sh b/build-kernel-mainline.sh
index 64de932d..acdcce82 100755
--- a/build-kernel-mainline.sh
+++ b/build-kernel-mainline.sh
@@ -2,7 +2,7 @@
 : "${LINUX_DIR:=src/linux}"
 : "${VENDOR_DTS:=vendor-dts}"
 : "${KEEP_SRC:=no}"
-: "${LINUX_OUT:=prebuilt/linux}"
+: "${LINUX_OUT:=prebuilt/linux-mainline}"
 : "${CROSS_COMPILE:=aarch64-linux-gnu-}"
 : "${BASE_CONFIG:=configs/minconfig-mainline}"
 : "${CONFIGS:=configs/linux}"