From ee4d74aca612a00990f7772eab148b5ce97c4bb4 Mon Sep 17 00:00:00 2001
From: Tycho Andersen <tycho@docker.com>
Date: Fri, 19 May 2017 13:45:42 -0600
Subject: [PATCH] projects: be more clever about merging kernel config

In particular, let's start with a defconfig and edit it, rather than try to
generate the config entirely from our own diff.

Signed-off-by: Tycho Andersen <tycho@docker.com>
---
 projects/kernel-config/makeconfig.sh | 53 +++++++++++++++++++---------
 1 file changed, 37 insertions(+), 16 deletions(-)

diff --git a/projects/kernel-config/makeconfig.sh b/projects/kernel-config/makeconfig.sh
index c7c92d3d6..98e675133 100755
--- a/projects/kernel-config/makeconfig.sh
+++ b/projects/kernel-config/makeconfig.sh
@@ -6,33 +6,43 @@ ARCH=$1
 KERNEL_SERIES=$2
 DEBUG=$3
 
-defconfig=defconfig
-if [ "${ARCH}" == "x86" ]; then
-    defconfig=x86_64_defconfig
-fi
-configpath="/linux/arch/${ARCH}/configs/${defconfig}"
+cd /linux && make defconfig
 
-cp /config/kernel_config.base "$configpath"
-
-function append_config()
+function merge_config()
 {
     config=$1
-
-    if [ -f "$config" ]; then
-        cat "$config" >> "$configpath"
+    if [ ! -f "$config" ]; then
+        return
     fi
+
+    # A slightly more intelligent merge algorithm: rather than just catting
+    # files together (and getting random results), let's explicitly delete the
+    # old setting, and then insert our new one.
+    while read line; do
+        if echo ${line} | grep "is not set" >/dev/null; then
+            cfg=$(echo ${line/ is not set/} | cut -c3-)
+        else
+            cfg=$(echo ${line} | cut -f1 -d=)
+        fi
+
+        sed -i -e "/${cfg} is not set/d" -e "/${cfg}=/d" /linux/.config
+        echo ${line} >> /linux/.config
+    done < "$config"
 }
 
-append_config "/config/kernel_config.${ARCH}"
-append_config "/config/kernel_config.${KERNEL_SERIES}"
-append_config "/config/kernel_config.${ARCH}.${KERNEL_SERIES}"
+cd /linux && make defconfig && make oldconfig
+
+merge_config "/config/kernel_config.base"
+merge_config "/config/kernel_config.${ARCH}"
+merge_config "/config/kernel_config.${KERNEL_SERIES}"
+merge_config "/config/kernel_config.${ARCH}.${KERNEL_SERIES}"
 
 if [ -n "${DEBUG}" ]; then
     sed -i sed -i 's/CONFIG_PANIC_ON_OOPS=y/# CONFIG_PANIC_ON_OOPS is not set/' /linux/arch/x86/configs/x86_64_defconfig
     append_config "/config/kernel_config.debug"
 fi
 
-cd /linux && make defconfig && make oldconfig
+cd /linux && make oldconfig
 
 # Let's make sure things are the way we want, i.e. every option we explicitly
 # set is set the same way in the resulting config.
@@ -42,7 +52,18 @@ function check_config()
 
     while read line; do
       if [ -n "${DEBUG}" ] && [ "$line" == "CONFIG_PANIC_ON_OOPS=y" ]; then continue; fi
-      grep "^${line}$" /linux/.config >/dev/null || (echo "$line set incorrectly" && false)
+      value="$(grep "^${line}$" /linux/.config || true)"
+
+      # It's okay to for the merging script to have simply not listed values we
+      # require to be unset.
+      if echo "${line}" | grep "is not set" >/dev/null && [ "$value" = "" ]; then
+          continue
+      fi
+      if [ "${value}" = "${line}" ]; then
+          continue
+      fi
+
+      echo "$line set incorrectly" && false
     done < $1
 }