docs/system/loongarch/virt.rst

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==========================================
loongson3 virt generic platform (``virt``)
==========================================

The ``virt`` machine use gpex host bridge, and there are some
emulated devices on virt board, such as loongson7a RTC device,
IOAPIC device, ACPI device and so on.

Supported devices
-----------------

The ``virt`` machine supports:
- Gpex host bridge
- Ls7a RTC device
- Ls7a IOAPIC device
- ACPI GED device
- Fw_cfg device
- PCI/PCIe devices
- Memory device
- CPU device. Type: la464.

CPU and machine Type
--------------------

The ``qemu-system-loongarch64`` provides emulation for virt
machine. You can specify the machine type ``virt`` and
cpu type ``la464``.

Boot options
------------

We can boot the LoongArch virt machine by specifying the uefi bios,
initrd, and linux kernel. And those source codes and binary files
can be accessed by following steps.

(1) Build qemu-system-loongarch64:

.. code-block:: bash

  ./configure --disable-rdma --disable-pvrdma --prefix=/usr \
              --target-list="loongarch64-softmmu" \
              --disable-libiscsi --disable-libnfs --disable-libpmem \
              --disable-glusterfs --enable-libusb --enable-usb-redir \
              --disable-opengl --disable-xen --enable-spice \
              --enable-debug --disable-capstone --disable-kvm \
              --enable-profiler
  make -j8

(2) Set cross tools:

.. code-block:: bash

  wget https://github.com/loongson/build-tools/releases/download/2022.09.06/loongarch64-clfs-6.3-cross-tools-gcc-glibc.tar.xz

  tar -vxf loongarch64-clfs-6.3-cross-tools-gcc-glibc.tar.xz  -C /opt

  export PATH=/opt/cross-tools/bin:$PATH
  export LD_LIBRARY_PATH=/opt/cross-tools/lib:$LD_LIBRARY_PATH
  export LD_LIBRARY_PATH=/opt/cross-tools/loongarch64-unknown-linux-gnu/lib/:$LD_LIBRARY_PATH

Note: You need get the latest cross-tools at https://github.com/loongson/build-tools

(3) Build BIOS:

    See: https://github.com/tianocore/edk2-platforms/tree/master/Platform/Loongson/LoongArchQemuPkg#readme

Note: To build the release version of the bios,  set --buildtarget=RELEASE,
      the bios file path:  Build/LoongArchQemu/RELEASE_GCC5/FV/QEMU_EFI.fd

(4) Build kernel:

.. code-block:: bash

  git clone https://github.com/loongson/linux.git

  cd linux

  git checkout loongarch-next

  make ARCH=loongarch CROSS_COMPILE=loongarch64-unknown-linux-gnu- loongson3_defconfig

  make ARCH=loongarch CROSS_COMPILE=loongarch64-unknown-linux-gnu- -j32

Note: The branch of linux source code is loongarch-next.
      the kernel file: arch/loongarch/boot/vmlinuz.efi

(5) Get initrd:

  You can use busybox tool and the linux modules to make a initrd file. Or you can access the
  binary files: https://github.com/yangxiaojuan-loongson/qemu-binary

.. code-block:: bash

  git clone https://github.com/yangxiaojuan-loongson/qemu-binary

Note: the initrd file is ramdisk

(6) Booting LoongArch:

.. code-block:: bash

  $ ./build/qemu-system-loongarch64 -machine virt -m 4G -cpu la464 \
      -smp 1 -bios QEMU_EFI.fd -kernel vmlinuz.efi -initrd ramdisk \
      -serial stdio   -monitor telnet:localhost:4495,server,nowait \
      -append "root=/dev/ram rdinit=/sbin/init console=ttyS0,115200" \
      --nographic