Support i386/32-bit kernel builds

Author: gsingh93

Makefile

@@ -26,7 +26,7 @@ ifeq ($(ARCH),aarch64)
 else ifeq ($(ARCH),x86)
   $(warning $(YELLOW)Incorrect architecture 'x86', using 'x86_64' instead $(NC))
   ARCH := x86_64
-else ifeq ($(filter x86_64 arm64,$(ARCH)),)
+else ifeq ($(filter x86_64 arm64 i386,$(ARCH)),)
   $(error Invalid architecture $(ARCH))
 endif
 
@@ -39,7 +39,7 @@ clean: linux_clean tools-vm_clean
 .PHONY: help
 help:
 	@echo '$(GREEN)General Environment Variables:$(NC)'
-	@echo '   ARCH                             - Specify one of the supported architectures: x86_64, arm64 (default: x86_64)'
+	@echo '   ARCH                             - Specify one of the supported architectures: x86_64, i386, arm64 (default: x86_64)'
 	@echo '   ACK                              - Set to 1 if building ACK instead of the Linux kernel. Does not need to be set for `ack` and `run-ack` targets (default: 0)'
 	@echo '   VERBOSE                          - Set to 1 to enable verbose output (default: 0)'
 	@echo ''
@@ -139,6 +139,9 @@ LINUX_CONFIG := $(LINUX_OUT)/.config
 ifeq ($(ARCH),x86_64)
   TARGET := x86_64-pc-linux-gnu
   KERNEL_IMAGE := $(LINUX_OUT)/arch/$(ARCH)/boot/bzImage
+else ifeq ($(ARCH),i386)
+  TARGET := i386-pc-linux-gnu
+  KERNEL_IMAGE := $(LINUX_OUT)/arch/$(ARCH)/boot/bzImage
 else ifeq ($(ARCH),arm64)
   TARGET := aarch64-linux-gnu
   KERNEL_IMAGE := $(LINUX_OUT)/arch/$(ARCH)/boot/Image
@@ -382,7 +385,9 @@ ifeq ($(ARCH),x86_64)
   ifneq ($(CI),true)
     QEMU_ARGS += -accel kvm
   endif
-
+else ifeq ($(ARCH),i386)
+  QEMU_BIN := qemu-system-i386
+  QEMU_KERNEL_CMDLINE += console=ttyS0
 else
   QEMU_BIN := qemu-system-aarch64
   QEMU_KERNEL_CMDLINE += console=ttyAMA0