From b14df228d7c4fe6e86e7f8a4998e9ccf4967b678 Mon Sep 17 00:00:00 2001 From: Stafford Horne Date: Fri, 1 Jul 2022 08:29:17 +0900 Subject: [PATCH] docs/system: openrisc: Add OpenRISC documentation Reviewed-by: Richard Henderson Signed-off-by: Stafford Horne --- docs/system/openrisc/cpu-features.rst | 15 ++++++ docs/system/openrisc/emulation.rst | 17 +++++++ docs/system/openrisc/or1k-sim.rst | 43 ++++++++++++++++ docs/system/openrisc/virt.rst | 50 +++++++++++++++++++ docs/system/target-openrisc.rst | 71 +++++++++++++++++++++++++++ docs/system/targets.rst | 1 + 6 files changed, 197 insertions(+) create mode 100644 docs/system/openrisc/cpu-features.rst create mode 100644 docs/system/openrisc/emulation.rst create mode 100644 docs/system/openrisc/or1k-sim.rst create mode 100644 docs/system/openrisc/virt.rst create mode 100644 docs/system/target-openrisc.rst diff --git a/docs/system/openrisc/cpu-features.rst b/docs/system/openrisc/cpu-features.rst new file mode 100644 index 0000000000..aeb65e22ff --- /dev/null +++ b/docs/system/openrisc/cpu-features.rst @@ -0,0 +1,15 @@ +CPU Features +============ + +The QEMU emulation of the OpenRISC architecture provides following built in +features. + +- Shadow GPRs +- MMU TLB with 128 entries, 1 way +- Power Management (PM) +- Programmable Interrupt Controller (PIC) +- Tick Timer + +These features are on by default and the presence can be confirmed by checking +the contents of the Unit Presence Register (``UPR``) and CPU Configuration +Register (``CPUCFGR``). diff --git a/docs/system/openrisc/emulation.rst b/docs/system/openrisc/emulation.rst new file mode 100644 index 0000000000..0af898ab20 --- /dev/null +++ b/docs/system/openrisc/emulation.rst @@ -0,0 +1,17 @@ +OpenRISC 1000 CPU architecture support +====================================== + +QEMU's TCG emulation includes support for the OpenRISC or1200 implementation of +the OpenRISC 1000 cpu architecture. + +The or1200 cpu also has support for the following instruction subsets: + +- ORBIS32 (OpenRISC Basic Instruction Set) +- ORFPX32 (OpenRISC Floating-Point eXtension) + +In addition to the instruction subsets the QEMU TCG emulation also has support +for most Class II (optional) instructions. + +For information on all OpenRISC instructions please refer to the latest +architecture manual available on the OpenRISC website in the +`OpenRISC Architecture `_ section. diff --git a/docs/system/openrisc/or1k-sim.rst b/docs/system/openrisc/or1k-sim.rst new file mode 100644 index 0000000000..ef10439737 --- /dev/null +++ b/docs/system/openrisc/or1k-sim.rst @@ -0,0 +1,43 @@ +Or1ksim board +============= + +The QEMU Or1ksim machine emulates the standard OpenRISC board simulator which is +also the standard SoC configuration. + +Supported devices +----------------- + + * 16550A UART + * ETHOC Ethernet controller + * SMP (OpenRISC multicore using ompic) + +Boot options +------------ + +The Or1ksim machine can be started using the ``-kernel`` and ``-initrd`` options +to load a Linux kernel and optional disk image. + +.. code-block:: bash + + $ qemu-system-or1k -cpu or1220 -M or1k-sim -nographic \ + -kernel vmlinux \ + -initrd initramfs.cpio.gz \ + -m 128 + +Linux guest kernel configuration +"""""""""""""""""""""""""""""""" + +The 'or1ksim_defconfig' for Linux openrisc kernels includes the right +drivers for the or1ksim machine. If you would like to run an SMP system +choose the 'simple_smp_defconfig' config. + +Hardware configuration information +"""""""""""""""""""""""""""""""""" + +The ``or1k-sim`` 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. 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. diff --git a/docs/system/target-openrisc.rst b/docs/system/target-openrisc.rst new file mode 100644 index 0000000000..22cb2217a6 --- /dev/null +++ b/docs/system/target-openrisc.rst @@ -0,0 +1,71 @@ +.. _OpenRISC-System-emulator: + +OpenRISC System emulator +~~~~~~~~~~~~~~~~~~~~~~~~ + +QEMU can emulate 32-bit OpenRISC CPUs using the ``qemu-system-or1k`` executable. + +OpenRISC CPUs are generally built into "system-on-chip" (SoC) designs that run +on FPGAs. These SoCs are based on the same core architecture as the or1ksim +(the original OpenRISC instruction level simulator) which QEMU supports. For +this reason QEMU does not need to support many different boards to support the +OpenRISC hardware ecosystem. + +The OpenRISC CPU supported by QEMU is the ``or1200``, it supports an MMU and can +run linux. + +Choosing a board model +====================== + +For QEMU's OpenRISC system emulation, you must specify which board model you +want to use with the ``-M`` or ``--machine`` option; the default machine is +``or1k-sim``. + +If you intend to boot Linux, it is possible to have a single kernel image that +will boot on any of the QEMU machines. To do this one would compile all required +drivers into the kernel. This is possible because QEMU will create a device tree +structure that describes the QEMU machine and pass a pointer to the structure to +the kernel. The kernel can then use this to configure itself for the machine. + +However, typically users will have specific firmware images for a specific machine. + +If you already have a system image or a kernel that works on hardware and you +want to boot with QEMU, check whether QEMU lists that machine in its ``-machine +help`` output. If it is listed, then you can probably use that board model. If +it is not listed, then unfortunately your image will almost certainly not boot +on QEMU. (You might be able to extract the filesystem and use that with a +different kernel which boots on a system that QEMU does emulate.) + +If you don't care about reproducing the idiosyncrasies of a particular +bit of hardware, such as small amount of RAM, no PCI or other hard disk, etc., +and just want to run Linux, the best option is to use the ``virt`` board. This +is a platform which doesn't correspond to any real hardware and is designed for +use in virtual machines. You'll need to compile Linux with a suitable +configuration for running on the ``virt`` board. ``virt`` supports PCI, virtio +and large amounts of RAM. + +Board-specific documentation +============================ + +.. + This table of contents should be kept sorted alphabetically + by the title text of each file, which isn't the same ordering + as an alphabetical sort by filename. + +.. toctree:: + :maxdepth: 1 + + openrisc/or1k-sim + openrisc/virt + +Emulated CPU architecture support +================================= + +.. toctree:: + openrisc/emulation + +OpenRISC CPU features +===================== + +.. toctree:: + openrisc/cpu-features diff --git a/docs/system/targets.rst b/docs/system/targets.rst index 9dcd95dd84..224fadae71 100644 --- a/docs/system/targets.rst +++ b/docs/system/targets.rst @@ -21,6 +21,7 @@ Contents: target-m68k target-mips target-ppc + target-openrisc target-riscv target-rx target-s390x