build a kernel, using malta_kvm_defconfig

(there's a lot in this config that I don't think is needed)

tests/kernel/run.sh

@@ -0,0 +1,13 @@
+set -e
+NIXPKGS_ALLOW_UNSUPPORTED_SYSTEM=1 nix-build  -I liminix-config=./tests/smoke/configuration.nix --arg device "import ./devices/$DEVICE.nix" -A outputs.kernel.vmlinux -o vmlinux $*
+
+TESTS=$(cat <<"EOF"
+
+trap 'echo "command $(eval echo $BASH_COMMAND) failed with exit code $?"; exit 1' ERR
+test -f vmlinux
+file -L vmlinux | grep ' ELF 32-bit MSB executable, MIPS'
+EOF
+     )
+
+
+nix-shell -p s6-rc -p squashfsTools --run "$TESTS" || exit 1