makefile: autodetect target arch for builds

Signed-off-by: Mikhail Sakhnov <mikhail@skhnv.me>

Makefile

@@ -19,8 +19,17 @@ GOOS ?= $(shell go env GOOS)
 
 # The target architecture for linux kernel. Possible values: amd64 or arm64.
 # Any other supported by linux kernel architecture could be added by introducing new build step into neonvm/hack/kernel/Dockerfile.kernel-builder
-KERNEL_TARGET_ARCH ?= amd64
-TARGET_ARCH ?= amd64
+UNAME_ARCH := $(shell uname -m)
+ifeq ($(UNAME_ARCH),x86_64)
+    KERNEL_TARGET_ARCH ?= amd64
+    TARGET_ARCH ?= amd64
+else ifeq ($(UNAME_ARCH),aarch64)
+    KERNEL_TARGET_ARCH ?= arm64
+    TARGET_ARCH ?= arm64
+else
+    $(error Unsupported architecture: $(UNAME_ARCH))
+endif
+
 # Get the currently used golang base path
 GOPATH=$(shell go env GOPATH)
 # Get the currently used golang install path (in GOPATH/bin, unless GOBIN is set)
@@ -264,21 +273,16 @@ ifndef ignore-not-found
   ignore-not-found = false
 endif
 
-# Build the kernel for the amd64 architecture. Uses generic target.
-.PHONY: kernel_amd64
-kernel_amd64: KERNEL_TARGET_ARCH=amd64
-kernel_amd64: kernel
-
-# Build the kernel for the arm64 architecture. Uses generic target.
-.PHONY: kernel_arm64
-kernel_arm64: KERNEL_TARGET_ARCH=arm64
-kernel_arm64: kernel
+# Build the kernel for the current architecture. Uses generic target.
+.PHONY: kernel
+kernel: KERNEL_TARGET_ARCH=$(TARGET_ARCH)
+kernel: build_kernel
 
 # Build the kernel for the target architecture.
 # The builder image platform is not specified because the kernel is built for the target architecture using crosscompilation.
 # Target is generic and can be used for any supported architecture by specifying the KERNEL_TARGET_ARCH variable.
-.PHONY: kernel
-kernel: ## Build linux kernel.
+.PHONY: build_kernel
+build_kernel: ## Build linux kernel.
 	rm -f neonvm-kernel/vmlinuz; \
 	linux_config=$$(ls neonvm-kernel/linux-config-*) \
 	kernel_version=$${linux_config##*-} \
@@ -394,12 +398,9 @@ load-example-vms: check-local-context kubectl kind k3d ## Load the testing VM im
 	@if [ $$($(KUBECTL) config current-context) = kind-$(CLUSTER_NAME) ]; then $(KIND) load docker-image $(E2E_TESTS_VM_IMG) --name $(CLUSTER_NAME); fi
 
 .PHONY: example-vms
+example-vms: TARGET_ARCH=$(TARGET_ARCH)
 example-vms: docker-build-examples load-example-vms ## Build and push the testing VM images to the kind/k3d cluster.
 
-.PHONY: example-vms-arm64
-example-vms-arm64: TARGET_ARCH=arm64
-example-vms-arm64: example-vms 
-
 .PHONY: load-pg16-disk-test
 load-pg16-disk-test: check-local-context kubectl kind k3d ## Load the pg16-disk-test VM image to the kind/k3d cluster.
 	@if [ $$($(KUBECTL) config current-context) = k3d-$(CLUSTER_NAME) ]; then $(K3D) image import $(PG16_DISK_TEST_IMG) --cluster $(CLUSTER_NAME) --mode direct; fi