xemu/target/loongarch

- Introduction

  LoongArch is the general processor architecture of Loongson.

  The following versions of the LoongArch core are supported
    core: 3A5000
    https://github.com/loongson/LoongArch-Documentation/releases/download/2021.08.17/LoongArch-Vol1-v1.00-EN.pdf

  We can get the latest loongarch documents at https://github.com/loongson/LoongArch-Documentation/tags.


- System emulation

  You can reference docs/system/loongarch/loongson3.rst to get the information about system emulation of LoongArch.

- Linux-user emulation

  We already support Linux user emulation. We can use LoongArch cross-tools to build LoongArch executables on X86 machines,
  and We can also use qemu-loongarch64 to run LoongArch executables.

  1. Config cross-tools env.

     see System emulation.

  2. Test tests/tcg/multiarch.

     ./configure  --static  --prefix=/usr  --disable-werror --target-list="loongarch64-linux-user" --enable-debug

     cd build

     make && make check-tcg

  3. Run LoongArch system basic command with loongarch-clfs-system.

     - Config clfs env.

       wget https://github.com/loongson/build-tools/releases/download/2022.05.29/loongarch64-clfs-system-5.0.tar.bz2

       tar -vxf loongarch64-clfs-system-5.0.tar.bz2 -C /opt/clfs

       cp /opt/clfs/lib64/ld-linux-loongarch-lp64d.so.1  /lib64

       export LD_LIBRARY_PATH="/opt/clfs/lib64"

     - Run LoongArch system basic command.

       ./qemu-loongarch64  /opt/clfs/usr/bin/bash
       ./qemu-loongarch64  /opt/clfs/usr/bin/ls
       ./qemu-loongarch64  /opt/clfs/usr/bin/pwd

- Note.
  We can get the latest LoongArch documents or LoongArch tools at https://github.com/loongson/