Move the bootrom to the ROM by engdoreis · Pull Request #447 · lowRISC/mocha

engdoreis · 2026-04-18T10:42:39Z

This PR:

Move the bootrom to the ROM
Move all tests to run on DRAM rather than SRAM.
Enable all verilator tests to use the bootrom.

marnovandermaas

This is a very cool PR. Just a few nits from my end and we need to make sure to test the DV run to make sure nothing breaks.

marnovandermaas · 2026-04-24T08:19:18Z

We need to make sure to run and check this before merging.

ziuziakowska

These are really great changes, I just have some nits and comments.

ziuziakowska · 2026-04-24T10:05:45Z

Something to think about: Maybe we could flip the condition to be NO_FPGA/SKIP_FPGA as that could stand out more, and it makes more sense with comments/TODOs explaining why that is there instead of why FPGA isn't there.

I think this is a good idea.

This PR is tool large already, so I opened an issue: #477

ziuziakowska · 2026-04-24T10:17:41Z

Maybe we could have a lib/boot/linkerscript or lib/boot/ld subdirectory to contain these, as there are quite a few now.

ziuziakowska · 2026-04-24T10:44:41Z

Doesn't need to be done in this PR, but now we can remove this runner and have Verilator tests run the binary directly.

I like the idea, but rather than fixing the path to verilator, we should use cmake to find it. So I'll leave it to a next PR.

AlexJones0

LGTM, with a few small nits & questions.

martin-velay · 2026-04-27T07:15:31Z

@thommythomaso, can you take a look at the RTL change of this commit: "[hw] Fix error sram error in dv"

The bootrom expect pin 8 to be pulled down to enter bootstrap mode, some making all pins up by default would skip bootstrap in verilator. Signed-off-by: Douglas Reis <doreis@lowrisc.org>

Macros share the scope with the caller, which can lead to undefined behaviour in complex macros.

To start from a clean state, otherwise a dram will never boot if sram is valid.

marnovandermaas · 2026-04-28T15:20:35Z

This patch can now be removed due to the DRAM fix PR.

marnovandermaas

This all looks good to me. Let's make sure that the top-level DV passes before merging but after that I'm happy for this to be merged.

AlexJones0

LGTM, thanks for the work on this.

I'm assuming the SRAM HW change is correct in that we cannot have sram_we when we are trying to read data, but I don't know enough about mocha's SRAM to validate that myself.

Signed-off-by: Douglas Reis <doreis@lowrisc.org>

The axi_to_detailed_mem module requires a valid read request to be accompanied by every write. This is problematic since at the start of time the content of SRAM is understandably undefined. Instead of feeding don't cares through the module alongside an rvalid signal. Now this feeds a recognisable hex sequence through the module so that it still works but it is also somewhat detectable if this read propagates to the output.

AlexJones0 · 2026-04-28T17:37:42Z

    build_cmd = ["cmake", "--build", build_dir, "-v", "--target"]
    install_cmd = ["cmake", "--install", build_dir, "--prefix", out_dir, "--component"]
-    for img in args.sw_images:
+    for img in args.sw_images.split():


Nit: if it can be done quickly, we should look into what part of DVSim / the HJSON flows is requiring us to do this and fix it there instead. This isn't a problem at all since we're running on Linux but is a bit of a code smell generally if it can be avoided.

engdoreis force-pushed the bootrom-verilator branch 13 times, most recently from 2d5ef23 to 5a4aeab Compare April 23, 2026 16:32

engdoreis changed the title ~~[wip] Run tests on DRAM~~ [wip] Move the bootrom to the ROM Apr 23, 2026

engdoreis changed the title ~~[wip] Move the bootrom to the ROM~~ Move the bootrom to the ROM Apr 23, 2026

engdoreis force-pushed the bootrom-verilator branch from 5a4aeab to 4ea2a85 Compare April 23, 2026 17:12

engdoreis marked this pull request as ready for review April 23, 2026 17:13

engdoreis requested review from AlexJones0, marnovandermaas and ziuziakowska and removed request for ziuziakowska April 23, 2026 17:13

marnovandermaas reviewed Apr 24, 2026

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engdoreis force-pushed the bootrom-verilator branch 2 times, most recently from cf21f52 to fb93064 Compare April 24, 2026 10:39

ziuziakowska reviewed Apr 24, 2026

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AlexJones0 approved these changes Apr 24, 2026

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engdoreis force-pushed the bootrom-verilator branch from fb93064 to 3c3895e Compare April 24, 2026 15:42

engdoreis marked this pull request as draft April 24, 2026 16:00

engdoreis force-pushed the bootrom-verilator branch from 3c3895e to 5da738b Compare April 24, 2026 19:53

engdoreis force-pushed the bootrom-verilator branch 2 times, most recently from 31960e0 to ff6bb31 Compare April 27, 2026 13:50

marnovandermaas mentioned this pull request Apr 28, 2026

[sram] Writes accompanied by defined read data #475

Draft

engdoreis added 6 commits April 28, 2026 15:09

[sw] Enable more FPGA tests

332f34a

[verilator] Enable pull-ups for all GPIOs

4f96ce8

The bootrom expect pin 8 to be pulled down to enter bootstrap mode, some making all pins up by default would skip bootstrap in verilator. Signed-off-by: Douglas Reis <doreis@lowrisc.org>

[cmake] Convert macros into functions

514b946

Macros share the scope with the caller, which can lead to undefined behaviour in complex macros.

[cmake] Add arguments to function mocha_add_executable_artefacts

eca09ab

[sw] Split linker script into sram and dram

3458f1a

[bootrom] Clear boot slots on bootstrap

2b44cd2

To start from a clean state, otherwise a dram will never boot if sram is valid.

marnovandermaas reviewed Apr 28, 2026

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engdoreis force-pushed the bootrom-verilator branch from ff6bb31 to 93ecd0a Compare April 28, 2026 15:31

engdoreis marked this pull request as ready for review April 28, 2026 15:31

engdoreis added 3 commits April 28, 2026 15:36

[bootrom] Move bootrom to rom

37bf81a

[cmake] Define timeout for tests

dceea7a

[ci] Run verilator tests in parallel

13cc55e

engdoreis force-pushed the bootrom-verilator branch from 93ecd0a to 1bf9ba4 Compare April 28, 2026 15:36

engdoreis requested review from AlexJones0 and ziuziakowska April 28, 2026 15:44

AlexJones0 approved these changes Apr 28, 2026

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engdoreis and others added 4 commits April 28, 2026 17:36

[cmake] Enable all tests to run on DRAM

d607c91

[sw,timer] Adjust timer_smoketest to cope with slow dram execution

e45bf24

[dv] Enable bootrom for top level tests

cd96932

Signed-off-by: Douglas Reis <doreis@lowrisc.org>

engdoreis force-pushed the bootrom-verilator branch from 1bf9ba4 to 992a877 Compare April 28, 2026 17:37

AlexJones0 approved these changes Apr 28, 2026

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engdoreis merged commit f17b7f6 into lowRISC:main Apr 28, 2026
5 checks passed

engdoreis deleted the bootrom-verilator branch April 28, 2026 19:24

ziuziakowska mentioned this pull request Apr 29, 2026

Move test timeouts to CMake #458

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engdoreis commented Apr 18, 2026 •

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