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‎docs/linux-on-de0nano-multicore.md‎

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---
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title: SMP Linux on De0 Nano Multicore
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layout: page
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parent: Linux
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nav_order: 6
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---
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# Prerequisites
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#### Tutorials
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Run our [Linux on De0 Nano tutorial](linux-on-de0nano.html) to ensure you have:
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- A working version of OpenOCD
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- A UART connected to the De0 Nano development board
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- `fusesoc` - The [FuseSoC build system](../fusesoc.html).
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- OpenOCD 0.10.0 (As of 2025, versions 0.11.0 and 0.12.0 have jtag timing issues)
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- `or1k-elf-` Toolchain as installed in our [newlib tutorial](../newlib.html).
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- `or1k-none-linux-musl-` - OpenRISC musl linux userspace toolchain
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#### System
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Additionally for the Linux tutorial we will need:
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- An x86 Linux workstation
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- The `curl` and `git` command line utilities
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- A serial terminal emulator, here we use `picocom`
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- 2.5 GB of disk space
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#### Files
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We will download these below.
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- linux - Linux kernel source code
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- [busybox-small-rootfs-20250708.tar.xz](https://github.com/stffrdhrn/or1k-rootfs-build/releases/download/or1k-20250708/busybox-small-rootfs-20250708.tar.xz) - Linux rootfs for userspace programs
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# SMP Linux on De0 Nano Multicore Tutorial
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In this tutorial we will cover building a Symetrical Multi-Processing (SMP) Linux kernel and booting it on [De0 Nano](../de0_nano/index.html)
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with a [busybox](https://busybox.net) root filesystem. This builds on the De0 Nano
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hello world FGPA board bring up and the Linux on De0 Nano tutorials.
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In this tutorial we will be able to expirment with an OpenRISC design with 2 cpu's.
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We break this tutorial down into parts:
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- Downloading the pieces
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- Compiling the kernel
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- Building the FPGA bitstream
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- Running the kernel
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## Downloading the Pieces
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To get started we will create a temporary directory and setup our environment, if
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you plan to do a lot of OpenRISC development consider adding these tools to your
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`PATH` permanently.
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To get everything you need run:
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```bash
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mkdir /tmp/linux-on-de0nano-multicore/
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cd /tmp/linux-on-de0nano-multicore/
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# Get our config for openocd
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curl -L -O https://openrisc.io/tutorials/de0_nano/de0_nano.cfg
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# Clone kernel source, ~2GiB
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git clone --depth 1 --branch v7.0.0-rc1 https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux.git
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# Download a busybox rootfs and our toolchain
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curl -L -O https://github.com/stffrdhrn/or1k-rootfs-build/releases/download/or1k-20250708/busybox-small-rootfs-20250708.tar.xz
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# Add IP cores to the environment
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fusesoc library add fusesoc-cores https://github.com/fusesoc/fusesoc-cores
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fusesoc library add elf-loader https://github.com/fusesoc/elf-loader.git
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fusesoc library add openrisc-cores https://github.com/openrisc/openrisc-cores
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fusesoc library add de0_nano-multicore https://github.com/stffrdhrn/de0_nano-multicore.git
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# Check the SoC design is available
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fusesoc core show de0_nano-multicore
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# Extract software needed for the kernel
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tar -xf busybox-small-rootfs-20250708.tar.xz
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# Check the OpenRISC linux toolchain is on the path, if not see the Linux on De0 Nano tutorial
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or1k-none-linux-musl-gcc --version
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```
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## Compiling the Kernel
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To build a Linux kernel we use the toolchain, kernel source code and rootfs just downloaded
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in the following make commands:
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```bash
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make -C linux \
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ARCH=openrisc \
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CROSS_COMPILE=or1k-none-linux-musl- \
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de0_nano_multicore_defconfig
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make -C linux \
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-j$(nproc) \
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ARCH=openrisc \
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CROSS_COMPILE=or1k-none-linux-musl- \
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CONFIG_INITRAMFS_SOURCE="$PWD/busybox-small-rootfs-20250708/initramfs/ $PWD/busybox-small-rootfs-20250708/initramfs.devnodes"
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```
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The first command configures the kernel with the default configuration `de0_nano_multicore_defconfig` which is for the De0 Nano
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board using our Mutlicore design. The `make` arguments are as follows:
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* `-C linux` - This saves us from having to change directory, `make` will run from within the Linux source code directory.
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* `ARCH=openrisc` - This passes the `ARCH` variable to the build system selecting the OpenRISC architecture.
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* `CROSS_COMPILE=or1k-none-linux-musl-` - This passes the `CROSS_COMPILE` variable to the build system selecting our toolchain.
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* `de0_nano_multicore_defconfig` - The make target, configures the linux kernel for the build.
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The second command builds the kernel. The new argument is:
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* `CONFIG_INITRAMFS_SOURCE=...` - This configures the built in root filesystem.
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When running on machines with no disk capabilities such as De0 Nano we can use an [initfamfs](https://www.kernel.org/doc/Documentation/filesystems/ramfs-rootfs-initramfs.txt)
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that is built directly into our kernel ELF binary. This is one of the most
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simple ways to boot Linux but it means that our data is only in RAM and will be
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lost after reset. Also, it means that updating the rootfs userspace utilties
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requires rebuilding the kernel.
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## Building the FPGA bitstream
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As with the De0 Nano hello world tutorial we can build the bitstream with:
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```bash
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fusesoc run de0_nano-multicore
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```
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*Note*: The De0 Nano multicore design uses 16K or 73% of the Cyclone IV LEs
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compared to 10K or 49% for the single core design. Also, you may notice that
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the total number of memory bits in the multicore design is slightly less
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compared to the single core design as we shrank the cache sizes on each core to
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allow for the design to fit.
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See fitting details below:
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```
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$ tail build/de0_nano-multicore_1.1/default-quartus/de0_nano-multicore_1_1.fit.summary
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Timing Models : Final
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Total logic elements : 16,245 / 22,320 ( 73 % )
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Total combinational functions : 14,659 / 22,320 ( 66 % )
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Dedicated logic registers : 7,440 / 22,320 ( 33 % )
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Total registers : 7440
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Total pins : 53 / 154 ( 34 % )
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Total virtual pins : 0
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Total memory bits : 312,576 / 608,256 ( 51 % )
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Embedded Multiplier 9-bit elements : 12 / 132 ( 9 % )
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Total PLLs : 1 / 4 ( 25 % )
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$ tail ../or1k-de0nano/build/de0_nano_1.1/default-quartus/de0_nano_1_1.fit.summary
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Timing Models : Final
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Total logic elements : 10,980 / 22,320 ( 49 % )
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Total combinational functions : 9,706 / 22,320 ( 43 % )
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Dedicated logic registers : 5,472 / 22,320 ( 25 % )
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Total registers : 5472
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Total pins : 73 / 154 ( 47 % )
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Total virtual pins : 0
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Total memory bits : 327,936 / 608,256 ( 54 % )
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Embedded Multiplier 9-bit elements : 6 / 132 ( 5 % )
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Total PLLs : 1 / 4 ( 25 % )
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```
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## Running the Kernel
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*(Note: this step is the same as Linux on De0 Nano)*
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To start Linux on the De0 Nano development board we need to load the bitstream then
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upload the kernel image into RAM over the debug interface. The steps being:
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1. Program the FPGA bitstream onto the FPGA board
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2. Using GDB load the kernel image - including the embedded rootfs - into RAM
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3. Reset the FPGA design, kicking off the kernel boot process
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#### Terminal 1
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We can program the OpenRISC FPGA bitstream and Linux kernel to the board with
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the following commands.
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```bash
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fusesoc run de0_nano-multicore --pgm quartus
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# Run openocd in the background so we can use one terminal.
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openocd -f interface/altera-usb-blaster.cfg -f de0_nano.cfg > openocd.log 2>&1 &
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or1k-elf-gdb ./linux/vmlinux \
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-ex 'target remote :3333' \
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-ex 'monitor reset' \
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-ex 'monitor halt' \
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-ex load \
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-ex 'monitor reset' \
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-ex detach \
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-ex quit
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pkill openocd
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```
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The GDB command will connect to OpenOCD, then reset and halt the board making
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it ready to program. The `load` command will load the `vmlinux` ELF binary into
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the De0 Nano RAM. The next `monitor reset` command will reset the FPGA design
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kicking off the Linux boot process.
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In a second terminal while the FPGA board is running connect
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to the serial console using `picocom`.
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#### Terminal 2
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*(Note: this step is the same as Linux on De0 Nano)*
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We will use terminal 2 for connecting to the development board.
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Open `picocom` with the following:
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```bash
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cd /tmp/linux-on-de0nano-multicore/
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picocom -b 115200 /dev/ttyUSB0 --receive-cmd 'rx -vv' --send-cmd 'sx -vv'
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```
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To disconnect press `Ctrl-a` `Ctrl-q`
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To upload files to the board press `Ctrl-a` `Ctrl-s`
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## Example Boot Sequence
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For reference in the `picocom` terminal the boot sequence will look as follows:
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#### Terminal 2
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```
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[ 0.000000] Compiled-in FDT at (ptrval)
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[ 0.000000] Linux version 7.0.0-rc1-de0nano-smp (shorne@antec) (or1k-none-linux-musl-gcc (GCC) 15.1.0, GNU ld (GNU Binutils) 2.44) #2 SMP Thu Feb 26 21:37:09 GMT 2026
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[ 0.000000] OF: reserved mem: Reserved memory: No reserved-memory node in the DT
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[ 0.000000] CPU: OpenRISC-10 (revision 0) @50 MHz
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[ 0.000000] -- dmmu: 64 entries, 1 way(s)
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[ 0.000000] -- immu: 64 entries, 1 way(s)
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[ 0.000000] -- additional features:
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[ 0.000000] -- debug unit
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[ 0.000000] -- PIC
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[ 0.000000] -- timer
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[ 0.000000] Initial ramdisk not found
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[ 0.000000] Setting up paging and PTEs.
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[ 0.000000] map_ram: Memory: 0x0-0x2000000
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[ 0.000000] itlb_miss_handler (ptrval)
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[ 0.000000] dtlb_miss_handler (ptrval)
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[ 0.000000] OpenRISC Linux -- http://openrisc.io
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[ 0.000000] Zone ranges:
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[ 0.000000] Normal [mem 0x0000000000000000-0x0000000001ffffff]
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[ 0.000000] Movable zone start for each node
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[ 0.000000] Early memory node ranges
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[ 0.000000] node 0: [mem 0x0000000000000000-0x0000000001ffffff]
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[ 0.000000] Initmem setup node 0 [mem 0x0000000000000000-0x0000000001ffffff]
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[ 0.000000] percpu: Embedded 5 pages/cpu s16032 r0 d24928 u40960
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[ 0.000000] Kernel command line: earlycon
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[ 0.000000] earlycon: ns16550a0 at MMIO 0x90000000 (options '115200')
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[ 0.000000] printk: legacy bootconsole [ns16550a0] enabled
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[ 0.000000] printk: log buffer data + meta data: 16384 + 51200 = 67584 bytes
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[ 0.000000] Dentry cache hash table entries: 4096 (order: 1, 16384 bytes, linear)
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[ 0.000000] Inode-cache hash table entries: 2048 (order: 0, 8192 bytes, linear)
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[ 0.000000] Sorting __ex_table...
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[ 0.000000] Built 1 zonelists, mobility grouping on. Total pages: 4096
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[ 0.000000] mem auto-init: stack:all(zero), heap alloc:off, heap free:off
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[ 0.000000] mem_init_done ...........................................
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[ 0.000000] SLUB: HWalign=16, Order=0-1, MinObjects=0, CPUs=2, Nodes=1
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[ 0.000000] rcu: Hierarchical RCU implementation.
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[ 0.000000] rcu: RCU calculated value of scheduler-enlistment delay is 10 jiffies.
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[ 0.000000] NR_IRQS: 32, nr_irqs: 32, preallocated irqs: 0
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[ 0.000000] rcu: srcu_init: Setting srcu_struct sizes based on contention.
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[ 0.000000] clocksource: openrisc_timer: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 38225208935 ns
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[ 0.000000] 100.00 BogoMIPS (lpj=500000)
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[ 0.000000] pid_max: default: 32768 minimum: 301
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[ 0.010000] Mount-cache hash table entries: 2048 (order: 0, 8192 bytes, linear)
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[ 0.020000] Mountpoint-cache hash table entries: 2048 (order: 0, 8192 bytes, linear)
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[ 0.040000] VFS: Finished mounting rootfs on nullfs
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[ 0.120000] rcu: Hierarchical SRCU implementation.
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[ 0.120000] rcu: Max phase no-delay instances is 1000.
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[ 0.140000] Timer migration: 1 hierarchy levels; 8 children per group; 1 crossnode level
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[ 0.160000] smp: Bringing up secondary CPUs ...
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[ 0.190000] CPU1: Booted secondary processor
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[ 0.190000] CPU: OpenRISC-10 (revision 0) @50 MHz
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[ 0.190000] -- dmmu: 64 entries, 1 way(s)
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[ 0.190000] -- immu: 64 entries, 1 way(s)
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[ 0.190000] -- additional features:
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[ 0.190000] -- debug unit
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[ 0.190000] -- PIC
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[ 0.190000] -- timer
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[ 0.190000] Synchronize counters for CPU 1: done.
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[ 0.230000] smp: Brought up 1 node, 2 CPUs
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[ 0.260000] Memory: 19960K/32768K available (5412K kernel code, 167K rwdata, 776K rodata, 5383K init, 79K bss, 12096K reserved, 0K cma-reserved)
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[ 0.280000] devtmpfs: initialized
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[ 0.360000] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 19112604462750000 ns
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[ 0.370000] posixtimers hash table entries: 1024 (order: 0, 8192 bytes, linear)
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[ 0.370000] futex hash table entries: 512 (16384 bytes on 1 NUMA nodes, total 16 KiB, linear).
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[ 0.440000] NET: Registered PF_NETLINK/PF_ROUTE protocol family
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[ 0.540000] pps_core: LinuxPPS API ver. 1 registered
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[ 0.540000] pps_core: Software ver. 5.3.6 - Copyright 2005-2007 Rodolfo Giometti <giometti@linux.it>
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[ 0.550000] PTP clock support registered
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[ 0.620000] clocksource: Switched to clocksource openrisc_timer
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[ 0.740000] NET: Registered PF_INET protocol family
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[ 0.760000] IP idents hash table entries: 2048 (order: 1, 16384 bytes, linear)
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[ 0.800000] tcp_listen_portaddr_hash hash table entries: 1024 (order: 0, 8192 bytes, linear)
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[ 0.810000] Table-perturb hash table entries: 65536 (order: 5, 262144 bytes, linear)
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[ 0.820000] TCP established hash table entries: 2048 (order: 0, 8192 bytes, linear)
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[ 0.830000] TCP bind hash table entries: 2048 (order: 2, 32768 bytes, linear)
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[ 0.840000] TCP: Hash tables configured (established 2048 bind 2048)
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[ 0.850000] UDP hash table entries: 256 (order: 1, 14336 bytes, linear)
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[ 0.860000] UDP-Lite hash table entries: 256 (order: 1, 14336 bytes, linear)
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[ 0.880000] NET: Registered PF_UNIX/PF_LOCAL protocol family
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[ 0.910000] RPC: Registered named UNIX socket transport module.
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[ 0.920000] RPC: Registered udp transport module.
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[ 0.920000] RPC: Registered tcp transport module.
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[ 0.930000] RPC: Registered tcp-with-tls transport module.
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[ 0.940000] RPC: Registered tcp NFSv4.1 backchannel transport module.
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[ 0.990000] workingset: timestamp_bits=30 max_order=12 bucket_order=0
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[ 1.140000] ledtrig-cpu: registered to indicate activity on CPUs
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[ 1.170000] Serial: 8250/16550 driver, 4 ports, IRQ sharing disabled
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[ 1.260000] printk: legacy console [ttyS0] disabled
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[ 1.280000] 90000000.serial: ttyS0 at MMIO 0x90000000 (irq = 2, base_baud = 3125000) is a 16550A
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[ 1.290000] printk: legacy console [ttyS0] enabled
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[ 1.290000] printk: legacy console [ttyS0] enabled
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[ 1.310000] printk: legacy bootconsole [ns16550a0] disabled
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[ 1.310000] printk: legacy bootconsole [ns16550a0] disabled
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[ 1.340000] -- dcache: 4096 bytes total, 32 bytes/line, 128 set(s), 1 way(s)
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[ 1.350000] -- icache: 4096 bytes total, 32 bytes/line, 128 set(s), 1 way(s)
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[ 1.370000] -- dcache: 4096 bytes total, 32 bytes/line, 128 set(s), 1 way(s)
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[ 1.380000] -- icache: 4096 bytes total, 32 bytes/line, 128 set(s), 1 way(s)
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[ 1.500000] NET: Registered PF_PACKET protocol family
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[ 1.830000] clk: Disabling unused clocks
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[ 4.840000] Freeing unused kernel image (initmem) memory: 5376K
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[ 4.840000] This architecture does not have kernel memory protection.
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[ 4.850000] Run /init as init process
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ifconfig: SIOCSIFADDR: No such device
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route: SIOCADDRT: Network unreachable
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Please press Enter to activate this console. run-parts: /etc/network/if-pre-up.d: No such file or directory
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~ # uname -a
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Linux openrisc 7.0.0-rc1-de0nano-smp #2 SMP Thu Feb 26 21:37:09 GMT 2026 openrisc GNU/Linux
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~ # cat /proc/cpuinfo
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processor : 0
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cpu architecture : OpenRISC 1000 (1.1-rev0)
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cpu implementation id : 0x1
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cpu version : 0x50001
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frequency : 50000000
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immu : 64 entries, 1 ways
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dmmu : 64 entries, 1 ways
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bogomips : 100.00
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features : orbis32
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processor : 1
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cpu architecture : OpenRISC 1000 (1.1-rev0)
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cpu implementation id : 0x1
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cpu version : 0x50001
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frequency : 50000000
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immu : 64 entries, 1 ways
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dmmu : 64 entries, 1 ways
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bogomips : 100.00
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features : orbis32
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```
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## Further Reading
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- [de0_nano-multicore](https://github.com/stffrdhrn/de0_nano-multicore) - A De0 Nano Multicore OpenRISC SoC design
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- [Linux Releases](https://kernel.org) - Linux release tarballs
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- [OpenRISC toolchain Releases](https://github.com/stffrdhrn/or1k-toolchain-build/releases) - Toolchain point releases
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- [OpenRISC rootfs Releases](https://github.com/stffrdhrn/or1k-rootfs-build/releases) - Rootfs point release

‎docs/linux-on-de0nano.md‎

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title: Linux on De0 Nano
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nav_order: 5
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---
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# Prerequisites
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## Further Reading
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- [openrisc/or1ksim](https://github.com/openrisc/or1ksim) - The or1ksim home page and git repo
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- [de0_nano](https://github.com/olofk/de0_nano) - The De0 Nano OpenRISC design
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- [OpenRISC on De0 Nano](https://www.rs-online.com/designspark/booting-linux-on-a-de0-nano-with-orpsoc) - One of the first tutorials for Linux on the De0 Nano
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- [or1ksim Releases](https://github.com/openrisc/or1ksim/releases) - Nightly build and point release
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- [Linux Releases](https://kernel.org) - Linux release tarballs
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- [OpenRISC toolchain Releases](https://github.com/stffrdhrn/or1k-toolchain-build/releases) - Toolchain point releases

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