[][openwrt][common][bsp][Add readme]
[Description]
Add readme for preparing SDK
[Release-log]
N/A
Change-Id: Ia2296b9202915dfbc8430139cab30d976918d6b6
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/9275993
diff --git a/Readme.md b/Readme.md
new file mode 100644
index 0000000..a01191f
--- /dev/null
+++ b/Readme.md
@@ -0,0 +1,78 @@
+# Brief introduction for using MediaTek released OpenWrt SDK
+
+## 1. Build system setup
+
+- Please refer to https://openwrt.org/docs/guide-developer/toolchain/install-buildsystem
+
+## 2. Clone vanilla OpenWrt
+
+Currently two release branches are supported:
+
+1. 21.02
+ This is the current in-use branch
+
+ ```bash
+ git clone -b openwrt-21.02 https://git.openwrt.org/openwrt/openwrt.git
+ ```
+
+2. master (will be 24.0x branch later)
+ The next version in development
+
+ ```bash
+ git clone https://git.openwrt.org/openwrt/openwrt.git
+ ```
+
+## 3. Add MediaTek OpenWrt feed
+
+```bash
+cd openwrt
+echo "src-git mtk_openwrt_feed https://git01.mediatek.com/openwrt/feeds/mtk-openwrt-feeds" >> feeds.conf.default
+./scripts/feeds update -a
+./scripts/feeds install -a
+```
+
+## 4. Apply MediaTek OpenWrt files and patches
+
+1. 21.02 branch
+
+ ```bash
+ cp -af ./feeds/mtk_openwrt_feed/21.02/files/* .
+ cp -af ./feeds/mtk_openwrt_feed/tools .
+ for file in $(find ./feeds/mtk_openwrt_feed/21.02/patches-base -name "*.patch" | sort); do patch -f -p1 -i ${file}; done
+ for file in $(find ./feeds/mtk_openwrt_feed/21.02/patches-feeds -name "*.patch" | sort); do patch -f -p1 -i ${file}; done
+ ```
+
+2. master branch
+
+ ```bash
+ cp -af ./feeds/mtk_openwrt_feed/master/files/* .
+ for file in $(find ./feeds/mtk_openwrt_feed/master/patches-base -name "*.patch" | sort); do patch -f -p1 -i ${file}; done
+ ```
+
+## 5. Configuration
+
+```bash
+make menuconfig
+```
+
+1. 21.02 branch
+
+ ```text
+ Target System -> MediaTek Ralink ARM
+ Subtarget -> MT7981 / MT7986 / MT7988
+ Target Profile -> select as needed
+ ```
+
+2. master branch
+
+ ```text
+ Target System -> MediaTek Ralink ARM
+ Subtarget -> Filogic 8x0 (MT798x)
+ Target Profile -> select as needed
+ ```
+
+## 6. Build
+
+```bash
+make V=s -j$(nproc)
+```