gem5: support variants

gem5/build

@@ -3,7 +3,7 @@ set -eu
 arch=x86_64
 cross_compile=
 j=
-outdir="$(pwd)/out"
+outdir="$(pwd)"
 while getopts a:c:j:o: OPT; do
   case "$OPT" in
     a)
@@ -28,7 +28,6 @@ system_dir="${outdir}/system"
 binaries_dir="${system_dir}/binaries"
 disks_dir="${system_dir}/disks"
 mkdir -p "$binaries_dir" "$disks_dir"
-cd "gem5"
 if [ "$arch" = x86_64 ]; then
   scons -j "$j" --ignore-style "${outdir}/build/X86/gem5.opt"
   f="${disks_dir}/linux-bigswap2.img"

gem5/external.mk

@@ -16,7 +16,13 @@ endif
 
 define GEM5_BUILD_CMDS
 	# Cannot pass "-c '$(TARGET_CROSS)'" here because the ARM build uses aarch64 for the bootloader...
-	cd '$(GEM5_SITE)' && ./build -a '$(ARCH)' -j '$(BR2_JLEVEL)' -o '$(GEM5_SITE)/../out/common/gem5'
+	cd '$(GEM5_LKMC_OUTDIR)' && '$(GEM5_SITE)/build' -a '$(ARCH)' -j '$(BR2_JLEVEL)'
+
+	# This would build using the submodule source out of tree.
+	# We gave up on it because in the end we still need the python scripts to match:
+	# we need to have an entire copy of the tree somwhere to switch between them.
+	#cd '$(GEM5_SITE)/gem5' && ../build -a '$(ARCH)' -j '$(BR2_JLEVEL)' -o '$(GEM5_SITE)/../out/common/gem5'
+
 	# This would build inside the buildroot directory as a more normal package.
 	#cd '$(@D)' && ./build -a '$(ARCH)' -j '$(BR2_JLEVEL)'