Update README.md

Author: JsBergbau

README.md

@@ -1,2 +1,33 @@
-# OpenJDK-Raspberry-Pi-Zero-W-armv6
-In this repository you find OpenJDK builds for Raspberry PI Zero W / armv6 architecture and also a tutorial how to build your own OpenJDK release in case you need that
+# OpenJDK RaspberryPi Zero W armv6hf
+In this repository you find OpenJDK builds for Raspberry PI Zero W / armv6hf architecture and also a tutorial how to build your own OpenJDK release in case you need that.
+
+Raspberry PI Zero and Zero W use BCM2835 SoC. Also original Raspberry PI uses this SoC. CPU architecture is 32 Bit ARMv6hf which means hardfloat support. 
+
+When trying to install Java from the official repository latest version is Java 11 and when trying to execute you get an error
+
+```
+sudo apt install default-jre
+
+pi@raspberrypi:~ $ java
+Error occurred during initialization of VM
+Server VM is only supported on ARMv7+ VFP
+```
+
+## Azul JDK
+
+At first place have a look at https://www.azul.com/downloads/?package=jdk
+
+They provide a working JDK 11 for Raspberry PI Zero W.
+
+Make sure to select ARM 32-bit HF and then have a look at the Architecture column. There must be "v6" present otherwise the package won't run on the Raspberry PI Zero W.
+
+Current (February 2022) there is no JDK17 for armv6.
+
+## Build the JDK on your own
+
+You can build your JDK on your own. Go to releases on the official repository https://github.com/openjdk/jdk/tags and select your desired version. For this repo I've chosen https://github.com/openjdk/jdk/releases/tag/jdk-17-ga 
+Download the source code and extract it
+
+You need a fitting crosscompiler to compile. There is currently none working so we have to build one ourselves. That is part of another article an Repo.
+
+