arch: Added initial OpenRISC port #83933

jhol · 2025-01-14T00:30:22Z

This patch adds support for the OpenRISC 1000 (or1k) architecture: a MIPS-like open hardware ISA which was first introduced in 2000.

This patch adds basic architecture support for the architecture, as well as a board and soc support for the Qemu virtual ork1ksim board.

github-actions · 2025-01-14T00:31:07Z

Hello @jhol, and thank you very much for your first pull request to the Zephyr project!
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jhol · 2025-01-14T00:32:45Z

@stffrdhrn Please feel free to comment. This work was the origin of the TTMR fix for Qemu.

jhol · 2025-01-14T01:43:21Z

The tests will not be able to complete because the tool-chain does not have the or1k-elf compiler or Qemu 9.2.0.

nashif · 2025-01-16T17:36:01Z

@jhol please split into multiple commits, see https://docs.zephyrproject.org/latest/contribute/contributor_expectations.html#multiple-commits-on-a-single-pr for reference.

jhol · 2025-01-16T22:52:42Z

please split into multiple commits

This has now been done!

jhol · 2025-01-16T23:18:31Z

v3 of the patch set makes the following changes:

Fixed file copyrights
Bumped copyright year from 2024 to 2025

jhol · 2025-01-17T00:12:34Z

v4 of the patch set makes the following changes:

Fixed warnings from check_compliance.py:
- Added my name to MAINTAINERS.yml
- Fixed directory paths in MAINTAINERS.yml
- Replaced obsolete config defines:
  - CONFIG_ARCH_HAS_CPU_IDLE_CUSTOM -> CONFIG_ARCH_HAS_CUSTOM_CPU_IDLE
  - CONFIG_ARCH_HAS_CPU_ATOMIC_IDLE_CUSTOM -> CONFIG_ARCH_HAS_CUSTOM_CPU_ATOMIC_IDLE
- Added missing braces
- Fixed typos
- Fixed a line length issue
- Added require blank lines

jhol · 2025-01-17T00:15:57Z

v5 of the patch set makes the following changes:

Fixed warnings from check_compliance.py:
- Fixed additional blank line

The OpenRISC 1000 architecture can be tested through the qemu_or1k emulated SoC and board. Because this emulated device has minimal external hardware by default, this patch enables a minimal suite of tests covering core kernel features for the CPU architecture. When running the test suite, OpenRISC was found to require additional stack space to prevent an overflow. Therefore, a minimal additional amount of storage: 128-bytes, was added that was found in practice to allow tests to complete. Note that Qemu version 9.2.0 or newer is required so as to include the following commit: commit 3eb43aeb164f1f83c97ff693c7d464b49755110c Author: Joel Holdsworth <[email protected]> Date: Fri Jun 7 15:29:33 2024 -0700 hw/openrisc: Fixed undercounting of TTCR in continuous mode This fixes a bug in the implementation of the emulated OpenRISC Tick Timer which prevents the Zephyr OpenRISC port from task-scheduling properly. Signed-off-by: Joel Holdsworth <[email protected]>

zephyrbot · 2025-02-18T21:54:08Z

The following west manifest projects have changed revision in this Pull Request:

Name	Old Revision	New Revision	Diff
picolibc	picolibc/picolibc@`82d62ed`	picolibc/picolibc@`4380f9a` (`debian`,`1.8.9-2`)	picolibc/[email protected]

Additional metadata changed:

Name	URL	Submodules	West cmds	`module.yml`
picolibc	✏

⛔ DNM label due to: 1 project with metadata changes

Note: This message is automatically posted and updated by the Manifest GitHub Action.

jhol · 2025-02-18T21:56:12Z

Here is v8 of the patch-set with the following changes:

Rebased on main
Upgrade picolibc to the new release which officially supports OpenRISC, and no longer requires a patch via a Zephyr patch.
Replaced used of CONFIG_ISR_STACK_SIZE with __z_interrupt_all_stacks_SIZEOF in stack initialization
Fixed a typo in a comment: s/OPENRISC/OpenRISC/
Fixed instances of incorrect usage of delay slots in assembly code
Improved comments in assembly code
Fixed typos in file header comments
Set frame pointer before entering z_prep_c
Replaced the terms "vector" and "ISR" with "exception" and "exception handler" which are more appropriate for the architecture.
Renamed _Fault function to z_openrisc_fault. This change was applied to multiple other architectures in Renamed _Fault to z_${ARCH}_fault #84535
Moved interrupt handling loop into C
Added chain_call and chain_call_reg assembly macros to simplify interrupt and syscall handling code
Added __reset and __start symbols to _reset_and__start and start section as aliases of the reset exception handler
Added support for CONFIG_SOC_RESET_HOOK
Keep D and I-Cache enabled in new threads
Set FLASH_SIZE and FLASH_BASE_ADDRESS on openrisc
Fixed non-build of irq_offload.c
Fixed #ifndef _ASMLANGUAGE in arch.h
Improved linker script with more features including support for XIP

jhol · 2025-02-18T22:00:12Z

@npitre I applied your suggestion concerning __z_interrupt_stack_SIZEOF.

Concerning the timer driver, it's not so clear to me what needs to happen here. To me, the OpenRISC timer driver doesn't look so very different from the Risc-V driver, but I'm happy to make any amendments.

npitre · 2025-02-18T22:38:22Z

Concerning the timer driver, it's not so clear to me what needs to happen
here. To me, the OpenRISC timer driver doesn't look so very different from
the Risc-V driver, but I'm happy to make any amendments.

You may look at commit 0ea64b3 for explanation and the needed changes,
mainly to sys_clock_set_timeout().

Also, if your sys_clock_hw_cycles_per_sec() resolves to a constant, then
you should consider not making your cyc_per_tick into a variable otherwise
everywhere you use it as a divisor it will induce important runtime overhead.
If it is a constant then the compiler will most likely optimize the division
at compile time with much simpler ALU instructions.

nashif · 2025-02-22T12:10:06Z

@jhol I managed to build the toolchain and qemu and was trying this PR. was able to build, but did not get any output from qemu:

west build -p -b qemu_or1k samples/synchronization/ -t run -- -DCONFIG_MINIMAL_LIBC=y

picolibc did not work for me, not sure what is going on:

/home/nashif/bin/zephyr-sdk-0.17.0/or1k-zephyr-elf/bin/../lib/gcc/or1k-zephyr-elf/12.2.0/../../../../or1k-zephyr-elf/bin/ld.bfd: /home/nashif/bin/zephyr-sdk-0.17.0/or1k-zephyr-elf/bin/../lib/gcc/../../picolibc/or1k-zephyr-elf/lib/./libc.a: error adding symbols: bad value
collect2: error: ld returned 1 exit status

@keith-packard ^^

running qemu:

Memory region         Used Size  Region Size  %age Used
             RAM:       32056 B       128 MB      0.02%
        IDT_LIST:          0 GB         2 KB      0.00%
Generating files from /home/nashif/zephyrproject/zephyr/build/zephyr/zephyr.elf for board: qemu_or1k
[120/121] To exit from QEMU enter: 'CTRL+a, x'[QEMU] CPU: or1k

jhol · 2025-02-22T16:19:54Z

Thanks for testing. What version of qemu do you have?

Note that Qemu version 9.2.0 or newer is required so as to include
the following commit:

    commit 3eb43aeb164f1f83c97ff693c7d464b49755110c
    Author: Joel Holdsworth <[email protected]>
    Date: Fri Jun 7 15:29:33 2024 -0700
    hw/openrisc: Fixed undercounting of TTCR in continuous mode

This fixes a bug in the implementation of the emulated OpenRISC Tick
Timer which prevents the Zephyr OpenRISC port from task-scheduling
properly.

nashif · 2025-02-22T17:52:35Z

Thanks for testing. What version of qemu do you have?

9.2.1, you can also get it from here https://github.com/zephyrproject-rtos/sdk-ng/actions/runs/13472947957/artifacts/2635045345 (PR zephyrproject-rtos/sdk-ng#871)

jhol · 2025-02-22T18:18:48Z

Thanks for testing. What version of qemu do you have?

9.2.1, you can also get it from here https://github.com/zephyrproject-rtos/sdk-ng/actions/runs/13472947957/artifacts/2635045345 (PR zephyrproject-rtos/sdk-ng#871)

Awesome. I'll test it out when I have time in the coming days

keith-packard · 2025-02-22T21:49:41Z

/home/nashif/bin/zephyr-sdk-0.17.0/or1k-zephyr-elf/bin/../lib/gcc/or1k-zephyr-elf/12.2.0/../../../../or1k-zephyr-elf/bin/ld.bfd: /home/nashif/bin/zephyr-sdk-0.17.0/or1k-zephyr-elf/bin/../lib/gcc/../../picolibc/or1k-zephyr-elf/lib/./libc.a: error adding symbols: bad value
collect2: error: ld returned 1 exit status

I've only been testing with the debian toolchain; haven't played with this one yet, and I haven't tried zephyr yet, just the picolibc test suite.

stffrdhrn · 2025-02-23T16:55:56Z

arch/openrisc/core/reboot.c

+{
+	ARG_UNUSED(type);
+
+	__asm__("l.nop 13");


Note in QEMU the openrisc virt platform does provide reboot via the syscon-reboot device. I guess we could add support for virt later?

carlescufi · 2025-02-24T20:48:33Z

~~Hi @jhol . Would you be willing and able to present this in the Architecture WG meeting? If so, please let me know of your availability here and I will schedule a date for you.~~

My mistake, this was already presented in my absence.

henrikbrixandersen · 2025-02-25T08:52:32Z

Architecture WG 2025-02-18:

@jhol gave a good introduction to the proposed port of Zephyr to the OpenRISC architecture.
NVIDIA is interested in backing this architecture port, and expect to be able to back it for at least 5 years.
The Zephyr SDK need to be updated to support the OpenRISC architecture (compiler suite, emu, …).

github-actions · 2025-04-27T00:40:29Z

This pull request has been marked as stale because it has been open (more than) 60 days with no activity. Remove the stale label or add a comment saying that you would like to have the label removed otherwise this pull request will automatically be closed in 14 days. Note, that you can always re-open a closed pull request at any time.

github-actions · 2025-08-02T00:41:12Z

This pull request has been marked as stale because it has been open (more than) 60 days with no activity. Remove the stale label or add a comment saying that you would like to have the label removed otherwise this pull request will automatically be closed in 14 days. Note, that you can always re-open a closed pull request at any time.

zgliu799 · 2025-10-22T11:00:38Z

@jhol Thanks for your zephyr openrisc port. It is working well in my mor1kx and marocchino FPGA board with just minor update.
Not sure why the zephyr openrisc port is not in merged in the master.
CC @stffrdhrn

jhol · 2025-10-22T16:27:28Z

@zgliu799 I'm glad it worked out for you.

Can you publish the fixes? I have a couple of small mods to-do on my side as well.

The project got stalled because I got busy with other work for the past few months. However, I would like to press ahead with the up-streaming.

The most major missing piece is getting an or1k GCC build included in the Zephyr tool-chain. I have this PR to add support, but I didn't get around to testing it yet.

zgliu799 · 2025-10-23T02:05:03Z

@jhol I did below modifications:
(1)Make sure r0 is 0 as below after hardware reset in exception.S.
exception_label 0x1, reset
l.movhi r0,0x0
(2)Comment out load_mac and store_mac in exception.S to workaround my RTL with FEATURE_MAC ="ENABLE". It seems RTL bug with FEATURE_MAC ="ENABLE".
The alternative workaround is to set RTL with FEATURE_MAC ="NONE"
(3)Updated .dts with the clock frequency and uart base address based on my board.

I tried the or1k-elf-gcc and also managed to build the or1k-zephyr-elf-gcc with your sdk-ng update . They are working in my setup to build zephyr.
or1k-zephyr-elf-gcc -v
Using built-in specs.
COLLECT_GCC=or1k-zephyr-elf-gcc
COLLECT_LTO_WRAPPER=/opt/or1k-zephyr-elf/bin/../libexec/gcc/or1k-zephyr-elf/15.2.0/lto-wrapper
Target: or1k-zephyr-elf
Configured with: /home/openrisc/or1k-build/build-workspace/build-or1k-zephyr-elf/.build/or1k-zephyr-elf/src/gcc/configure --build=x86_64-build_pc-linux-gnu --host=x86_64-build_pc-linux-gnu --target=or1k-zephyr-elf --prefix=/home/openrisc/or1k-build/build-workspace/output/or1k-zephyr-elf --exec_prefix=/home/openrisc/or1k-build/build-workspace/output/or1k-zephyr-elf --with-local-prefix=/home/openrisc/or1k-build/build-workspace/output/or1k-zephyr-elf/or1k-zephyr-elf --with-headers=/home/openrisc/or1k-build/build-workspace/output/or1k-zephyr-elf/or1k-zephyr-elf/include --with-newlib --enable-threads=no --disable-shared --with-pkgversion='crosstool-NG 1.28.0.1_403899e' --enable-__cxa_atexit --disable-libgomp --disable-libmudflap --disable-libmpx --disable-libssp --disable-libquadmath --disable-libquadmath-support --disable-libstdcxx-verbose --with-gmp=/home/openrisc/or1k-build/build-workspace/build-or1k-zephyr-elf/.build/or1k-zephyr-elf/buildtools --with-mpfr=/home/openrisc/or1k-build/build-workspace/build-or1k-zephyr-elf/.build/or1k-zephyr-elf/buildtools --with-mpc=/home/openrisc/or1k-build/build-workspace/build-or1k-zephyr-elf/.build/or1k-zephyr-elf/buildtools --with-isl=/home/openrisc/or1k-build/build-workspace/build-or1k-zephyr-elf/.build/or1k-zephyr-elf/buildtools --enable-lto --enable-target-optspace --disable-plugin --disable-nls --disable-multilib --enable-languages=c,c++
Thread model: single
Supported LTO compression algorithms: zlib zstd
gcc version 15.2.0 (crosstool-NG 1.28.0.1_403899e)

jhol · 2025-10-23T22:02:38Z

This PR has now been resurrected in #98160

zephyrbot requested review from TaiJuWu, aaronemassey, andyross, asemjonovs, ceolin, cfriedt, dcpleung, jeremybettis, nashif, npitre, peter-mitsis, stephanosio, teburd, tejlmand and yperess January 14, 2025 00:31

zephyrbot assigned dcpleung and nashif Jan 14, 2025

kartben added the area: Boards label Jan 16, 2025

jhol force-pushed the or1k-port branch from 9530f8b to d3ae553 Compare January 16, 2025 22:51

jhol force-pushed the or1k-port branch from d3ae553 to 5dbae60 Compare January 16, 2025 23:17

jhol force-pushed the or1k-port branch from 5dbae60 to 339eefb Compare January 17, 2025 00:08

jhol force-pushed the or1k-port branch from 339eefb to 9491bf8 Compare January 17, 2025 00:15

jhol force-pushed the or1k-port branch from 2b2a77d to 2f64a88 Compare February 18, 2025 21:49

zephyrbot added manifest manifest-picolibc DNM (manifest) This PR should not be merged (controlled by action-manifest) labels Feb 18, 2025

stffrdhrn reviewed Feb 23, 2025

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jhol mentioned this pull request Oct 23, 2025

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