Uber easy arch swap

README.md

@@ -225,11 +225,6 @@ And then tell GDB where the module was loaded with:
 
 The portability of the kernel and toolchains is amazing.
 
-If you already have an x86 build present, first:
-
-    cd buildroot
-    mv output output.x86~
-
 First ARM build:
 
     ./run -a arm

run

@@ -1,6 +1,5 @@
 #!/usr/bin/env bash
 set -e
-cd buildroot
 arch='x86_64'
 while getopts a: OPT > /dev/null 2>&1; do
   case "$OPT" in
@@ -19,6 +18,9 @@ case "$arch" in
     defconfig=qemu_arm_versatile_defconfig
     ;;
 esac
+
+./setoutarch "$arch"
+cd buildroot
 for p in $(find '../buildroot_patches/' -maxdepth 1 -name '*.patch' -print); do
     patch -N -r - -p 1 <"$p" || :
 done
@@ -26,7 +28,6 @@ make BR2_EXTERNAL="$(pwd)/../kernel_module" "$defconfig"
 # TODO Can't get rid of this for now.
 # http://stackoverflow.com/questions/44078245/is-it-possible-to-use-config-fragments-with-buildroots-config
 cat ../buildroot_config_fragment >> .config
-
 # HOST_QEMU_OPTS is a hack that happens to work because the QEMU package luckly uses += at all times.
 # It shouldn't be necessary in the first place: https://bugs.busybox.net/show_bug.cgi?id=9936
 # Even if were an autotools package, there is no general way currently to pass extra configs to it:
@@ -43,6 +44,5 @@ env \
   kernel_module-rebuild \
   all \
 ;
-
 cd ..
 ./runqemu "$@"

runqemu

@@ -43,6 +43,7 @@ done
 shift "$(($OPTIND - 1))"
 extra_flags="$extra_flags $@"
 
+./setoutarch "$arch"
 buildroot_out_dir='./buildroot/output'
 images_dir="$buildroot_out_dir/images"
 qemu_common="\
@@ -83,7 +84,6 @@ case "$arch" in
     "
   ;;
 esac
-echo "$cmd"
 if "$debug" && ! "$nographic" && [ ! "$arch" = 'arm'  ]; then
   eval "$cmd" &>/dev/null &
   # TODO: Ctrl +C gets sent to QEMU? Why? Does not happen if I run

setoutarch

@@ -0,0 +1,10 @@
+#!/usr/bin/env bash
+# Maintain different buildroot/output archs with symlinks.
+if [ "$#" -ne 1 ]; then
+  exit 1
+fi
+arch="$1"
+dst="output.${arch}~"
+src='buildroot/output'
+mkdir -p "buildroot/$dst"
+ln -fns "$dst" "$src"