loongson3 virt generic platform (virt) — QEMU documentation

# 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-loongarch-cpu.

## CPU and machine Type

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

## 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. booting command:

    $ qemu-system-loongarch64 -machine virt -m 4G -cpu la464-loongarch-cpu \
        -smp 1 -bios QEMU_EFI.fd -kernel vmlinuz.efi -initrd initrd.img \
        -append "root=/dev/ram rdinit=/sbin/init consol e=ttyS0,115200" \
        --nographic

Note: The running speed may be a little slow, as the performance of our qemu and uefi bios is not perfect, and it is being fixed.

2. cross compiler tools:

    wget https://github.com/loongson/build-tools/releases/download/ \
    2022.05.29/loongarch64-clfs-5.0-cross-tools-gcc-full.tar.xz

    tar -vxf loongarch64-clfs-5.0-cross-tools-gcc-full.tar.xz

3. qemu compile configure option:

    ./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

4. uefi bios source code and compile method:

    git clone https://github.com/loongson/edk2-LoongarchVirt.git

    cd edk2-LoongarchVirt

    git submodule update --init

    export PATH=$YOUR_COMPILER_PATH/bin:$PATH

    export WORKSPACE=`pwd`

    export PACKAGES_PATH=$WORKSPACE/edk2-LoongarchVirt

    export GCC5_LOONGARCH64_PREFIX=loongarch64-unknown-linux-gnu-

    edk2-LoongarchVirt/edksetup.sh

    make -C edk2-LoongarchVirt/BaseTools

    build --buildtarget=DEBUG --tagname=GCC5 --arch=LOONGARCH64  --platform=OvmfPkg/LoongArchQemu/Loongson.dsc

    build --buildtarget=RELEASE --tagname=GCC5 --arch=LOONGARCH64  --platform=OvmfPkg/LoongArchQemu/Loongson.dsc

The efi binary file path:

> Build/LoongArchQemu/DEBUG_GCC5/FV/QEMU_EFI.fd

> Build/LoongArchQemu/RELEASE_GCC5/FV/QEMU_EFI.fd

5. linux kernel source code and compile method:

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

    export PATH=$YOUR_COMPILER_PATH/bin:$PATH

    export LD_LIBRARY_PATH=$YOUR_COMPILER_PATH/lib:$LD_LIBRARY_PATH

    export LD_LIBRARY_PATH=$YOUR_COMPILER_PATH/loongarch64-unknown-linux-gnu/lib/:$LD_LIBRARY_PATH

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

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

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

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

Note: The branch of linux source code is loongarch-next.

6. initrd file:

> 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