Add README.md

Makefile

@@ -78,6 +78,7 @@ clean_staging:
 .PHONY: container
 container:
 	$(CONTAINER_CMD) build -t $(CONTAINER_IMAGE_TAG) $(ROOT_DIR)
+	@echo "New container image is tagged as: $(CONTAINER_IMAGE_TAG)"
 
 
 .PHONY: .test

README.md

@@ -0,0 +1,115 @@
+# ImageBuilder
+
+Brought to you by OERV team.
+
+## Overview
+
+It is driven by GNU Makefile for target management.
+
+It will produce:
+
+- RootFS tarball
+  - rpm-based package manager
+    - [x] yum
+  - [ ] ~~dpkg-based package manager~~
+  - Archiving method
+    - [x] tar.zst
+- Embedded system images for SBC-like devices
+  - Single disk image with all partitions inside
+    - [x] GUID partition table
+      - [x] Partition UUID
+      - [x] Partition GUID type and attributes
+      - [x] Partition name
+    - [ ] msdos parition table
+    - [ ] MTD
+  - [ ] Separated files for each filesystem
+  - Filesystems
+    - [x] vfat
+    - [x] ext4
+- Post-process for specific usage
+  - [ ] qcow2 format
+  - [ ] Vendor-defined package format
+
+It can be interrupted at any time, without harming your host OS.
+
+## Prerequirements
+
+- Root-mode docker with `--priviledged` option available
+  - May not be necessary in the future
+- rsync
+- GNU Makefile
+- ~~And other basic shell utils~~
+
+## Usage
+
+### Build New Images
+
+> Bash tab completition will print all available targets
+
+Firstly, let it build a container image for later use:
+
+```shell
+make container
+```
+
+It will be tagged and managed by docker.
+
+Listing all available targets:
+
+```shell
+make list
+```
+
+Build a single rootfs target:
+
+```shell
+make openEuler-24.03-LTS-SP1-base-rootfs
+```
+
+> Once a rootfs target is created, it will never be created again and will be used to build all related BSP targets.
+
+Build all rootfs targets one by one, under a different directory `/tmp/build`:
+
+```shell
+make O=/tmp/build openEuler-24.03-LTS-SP1-base-rootfs
+```
+
+Build all available BSP targets, parallelly:
+
+```shell
+make -j$(nproc) all_bsp
+```
+
+> BSP target will be rebuilt each time
+
+Cleanup:
+
+```shell
+make clean
+```
+
+### Add New Targets
+
+#### Add RootFS Targets
+
+1. Creating a directory for your distro under `receipes`
+2. Filling `receipes/${DISTRO_NAME}/distro.mk`, taking existing ones as reference
+3. Creating a directory for the distro release, under `receipes/${DISTRO_NAME}`
+4. Filling `receipes/${DISTRO_NAME}/${DISTRO_RELEASE}/release.mk`
+5. Creating a directory for rootfs receipe (such as minimal, base or desktop), under `receipes/${DISTRO_NAME}/${DISTRO_RELEASE}/userspace`
+6. Filling `receipes/${DISTRO_NAME}/${DISTRO_RELEASE}/userspace/${receipe}/receipe.mk`
+7. Listing required packages under `receipes/${DISTRO_NAME}/${DISTRO_RELEASE}/userspace/${receipe}/packages.d`
+8. Listing repo URLs required to install those packages under `receipes/${DISTRO_NAME}/${DISTRO_RELEASE}/userspace/${receipe}/repos.d`
+9. Listing scripts to be run after all package installation under ``receipes/${DISTRO_NAME}/${DISTRO_RELEASE}/userspace/${receipe}/post.d``
+
+#### Add BSP Targets
+
+TBD
+
+#### Common Usage
+
+##### `packages.d`
+
+##### `post.d`
+
+##### `repos.d`