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Diffstat (limited to 'docs/system/openrisc/virt.rst')
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diff --git a/docs/system/openrisc/virt.rst b/docs/system/openrisc/virt.rst new file mode 100644 index 0000000000..2fe61ac942 --- /dev/null +++ b/docs/system/openrisc/virt.rst @@ -0,0 +1,50 @@ +'virt' generic virtual platform +=============================== + +The ``virt`` board is a platform which does not correspond to any +real hardware; it is designed for use in virtual machines. +It is the recommended board type if you simply want to run +a guest such as Linux and do not care about reproducing the +idiosyncrasies and limitations of a particular bit of real-world +hardware. + +Supported devices +----------------- + + * PCI/PCIe devices + * 8 virtio-mmio transport devices + * 16550A UART + * Goldfish RTC + * SiFive Test device for poweroff and reboot + * SMP (OpenRISC multicore using ompic) + +Boot options +------------ + +The virt machine can be started using the ``-kernel`` and ``-initrd`` options +to load a Linux kernel and optional disk image. For example: + +.. code-block:: bash + + $ qemu-system-or1k -cpu or1220 -M or1k-sim -nographic \ + -device virtio-net-device,netdev=user -netdev user,id=user,net=10.9.0.1/24,host=10.9.0.100 \ + -device virtio-blk-device,drive=d0 -drive file=virt.qcow2,id=d0,if=none,format=qcow2 \ + -kernel vmlinux \ + -initrd initramfs.cpio.gz \ + -m 128 + +Linux guest kernel configuration +"""""""""""""""""""""""""""""""" + +The 'virt_defconfig' for Linux openrisc kernels includes the right drivers for +the ``virt`` machine. + +Hardware configuration information +"""""""""""""""""""""""""""""""""" + +The ``virt`` board automatically generates a device tree blob ("dtb") which it +passes to the guest. This provides information about the addresses, interrupt +lines and other configuration of the various devices in the system. + +The location of the DTB will be passed in register ``r3`` to the guest operating +system. |