Build gem5 through buildroot

Oh, btw, also make it work, since the build was completely broken since
the recent -K refactoring :0)

run

@@ -74,13 +74,15 @@ buildroot_dir="${root_dir}/buildroot"
 out_dir="${root_dir}/buildroot/output.${arch_dir}~"
 
 if "$gem5"; then
-  gem5_dir="${root_dir}/gem5/gem5"
+  build_dir="${out_dir}/build/gem5-1.0"
+  gem5_dir="${build_dir}/gem5"
   if [ "$arch" = x86_64 ]; then
     if "$kvm"; then
       extra_flags="$extra_flags --cpu-type=X86KvmCPU"
     fi
     cmd="\
-M5_PATH='${root_dir}/gem5/gem5-system' \
+M5_PATH='${build_dir}/system' \
+$debug_vm \
 '${gem5_dir}/build/X86/gem5.opt' \
 ${gem5opts} \
 '${gem5_dir}/configs/example/fs.py' \
@@ -92,7 +94,7 @@ $extra_flags \
 "
   elif [ "$arch" = arm ] || [ "$arch" = aarch64 ]; then
     cmd="\
-M5_PATH='${root_dir}/gem5/gem5-system' \
+M5_PATH='${build_dir}/system' \
 $debug_vm \
 '${gem5_dir}/build/ARM/gem5.opt' \
 ${gem5opts} \
@@ -102,7 +104,7 @@ ${gem5opts} \
 --dtb-file='${gem5_dir}/system/arm/dt/$([ "$arch" = arm ] && echo "armv7_gem5_v1_${cpus}cpu" || echo "armv8_gem5_v1_${cpus}cpu").dtb' \
 --kernel='${out_dir}/build/linux-custom/vmlinux' \
 --machine-type=VExpress_GEM5_V1 \
---num-cpus=${cpus} \
+--num-cpus='${cpus}' \
 $extra_flags \
 "
   fi
@@ -113,8 +115,8 @@ else
   extra_flags="${extra_flags_qemu} ${extra_flags}"
   images_dir="${out_dir}/images"
   qemu_common="\
-${debug_vm} \
-${out_dir}/host/usr/bin/qemu-system-${arch} \
+'${debug_vm}' \
+'${out_dir}/host/usr/bin/qemu-system-${arch}' \
 -m 128M \
 -monitor telnet::45454,server,nowait \
 -netdev user,hostfwd=tcp::45455-:45455,id=net0 \
@@ -141,7 +143,7 @@ ${out_dir}/host/usr/bin/qemu-system-${arch} \
 -device edu \
 -device lkmc_pci_min \
 -device virtio-net-pci,netdev=net0 \
--kernel ${images_dir}/bzImage \
+-kernel '${images_dir}/bzImage' \
 ${extra_flags} \
 "
     ;;
@@ -157,8 +159,8 @@ ${extra_flags} \
 -M versatilepb \
 -append '$root $extra_append' \
 -device rtl8139,netdev=net0 \
--dtb ${images_dir}/versatile-pb.dtb \
--kernel ${images_dir}/zImage \
+-dtb '${images_dir}/versatile-pb.dtb' \
+-kernel '${images_dir}/zImage' \
 -serial stdio \
 $extra_flags \
 "
@@ -172,7 +174,7 @@ $extra_flags \
 -append 'root=/dev/sda ${extra_append}' \
 -cpu cortex-a57 \
 -device virtio-net-device,netdev=net0 \
--kernel ${images_dir}/Image \
+-kernel '${images_dir}/Image' \
 -nographic \
 -serial stdio \
 ${extra_flags} \
@@ -188,7 +190,7 @@ ${extra_flags} \
 -append 'root=/dev/hda ${extra_append}' \
 -cpu I6400 \
 -device pcnet \
--kernel ${images_dir}/vmlinux \
+-kernel '${images_dir}/vmlinux' \
 -nographic \
 ${extra_flags} \
 "