target-openrisc.rst (2731B)
1 .. _OpenRISC-System-emulator: 2 3 OpenRISC System emulator 4 ~~~~~~~~~~~~~~~~~~~~~~~~ 5 6 QEMU can emulate 32-bit OpenRISC CPUs using the ``qemu-system-or1k`` executable. 7 8 OpenRISC CPUs are generally built into "system-on-chip" (SoC) designs that run 9 on FPGAs. These SoCs are based on the same core architecture as the or1ksim 10 (the original OpenRISC instruction level simulator) which QEMU supports. For 11 this reason QEMU does not need to support many different boards to support the 12 OpenRISC hardware ecosystem. 13 14 The OpenRISC CPU supported by QEMU is the ``or1200``, it supports an MMU and can 15 run linux. 16 17 Choosing a board model 18 ====================== 19 20 For QEMU's OpenRISC system emulation, you must specify which board model you 21 want to use with the ``-M`` or ``--machine`` option; the default machine is 22 ``or1k-sim``. 23 24 If you intend to boot Linux, it is possible to have a single kernel image that 25 will boot on any of the QEMU machines. To do this one would compile all required 26 drivers into the kernel. This is possible because QEMU will create a device tree 27 structure that describes the QEMU machine and pass a pointer to the structure to 28 the kernel. The kernel can then use this to configure itself for the machine. 29 30 However, typically users will have specific firmware images for a specific machine. 31 32 If you already have a system image or a kernel that works on hardware and you 33 want to boot with QEMU, check whether QEMU lists that machine in its ``-machine 34 help`` output. If it is listed, then you can probably use that board model. If 35 it is not listed, then unfortunately your image will almost certainly not boot 36 on QEMU. (You might be able to extract the filesystem and use that with a 37 different kernel which boots on a system that QEMU does emulate.) 38 39 If you don't care about reproducing the idiosyncrasies of a particular 40 bit of hardware, such as small amount of RAM, no PCI or other hard disk, etc., 41 and just want to run Linux, the best option is to use the ``virt`` board. This 42 is a platform which doesn't correspond to any real hardware and is designed for 43 use in virtual machines. You'll need to compile Linux with a suitable 44 configuration for running on the ``virt`` board. ``virt`` supports PCI, virtio 45 and large amounts of RAM. 46 47 Board-specific documentation 48 ============================ 49 50 .. 51 This table of contents should be kept sorted alphabetically 52 by the title text of each file, which isn't the same ordering 53 as an alphabetical sort by filename. 54 55 .. toctree:: 56 :maxdepth: 1 57 58 openrisc/or1k-sim 59 openrisc/virt 60 61 Emulated CPU architecture support 62 ================================= 63 64 .. toctree:: 65 openrisc/emulation 66 67 OpenRISC CPU features 68 ===================== 69 70 .. toctree:: 71 openrisc/cpu-features