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hw: Bump deps, adapt default AXI user bits #53

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merged 4 commits into from
Jul 18, 2023
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@micprog micprog commented Jul 11, 2023

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@micprog micprog requested a review from paulsc96 July 11, 2023 16:09
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paulsc96 commented Jul 11, 2023

After closer inspection, the whole AxiUserAmoDomain thing is more complicated than I remembered...

As-is, I think the default config is actually broken ☹️ The AxiUserAmoDomain may NOT be zero or map to zero, as zero is the implicit value assumed by non-atomic masters, including the DMA. This means that as-is, the DMA could disturb core atomics.

So I think this one will require a bit more thinking 🤔 Let's first maybe merge the AXI bump and git links.

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LGTM 👍

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micprog commented Jul 18, 2023

To briefly document the discussion we had:

  • Non-ATOP transactions do not use the atop user bits. Therefore, only ATOP masters need to care about having unique bits.
  • To allow for some customizability, the default value for all user bits can be set. For all ATOP-capable masters, unique user bits in the ATOP range need to be ensured. However, within this system, there is currently only a single ATOP-capable master (CVA6, serial link, and external masters should be appropriately handled externally). This will need to be adjusted for dual-core systems.
  • If other custom features are desired using the user bits, this will require internal modifications or can be set using the default.

@paulsc96 paulsc96 changed the title Adapt git links and AXI user config, bump AXI hw: Bump deps, adapt default AXI user bits Jul 18, 2023
@paulsc96 paulsc96 merged commit ea7648c into main Jul 18, 2023
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@paulsc96 paulsc96 deleted the michaero/axi_user branch July 18, 2023 17:38
MaistoV pushed a commit to MaistoV/cheshire_fork that referenced this pull request Aug 23, 2023
* Update git links

* Adapt ATOP configuration

* Add user defaults to all AXI masters

* fixup! Add user defaults to all AXI masters
Aquaticfuller pushed a commit that referenced this pull request Jul 16, 2024
Update safety island to support atomics
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