Set Verilator version v5.006

[rgantonio]

This PR sets the Verilator version to v5.006. This is more stable as it is in accordance with what the Snitch cluster is using.

Why need this?

• The CONVOLVE project must use the reduced AXI bandwidth to minimize routing congestion problems. The current AXI version they use is only working in v5.006 that's why they use it.

Nothing changes functionally and this is actually more "stable"

This will help PR #173 to finish building.

Please approve 😭

[jorendumoulin]

hmm okay

is there someone maintaining the AXI that fails with verilator?

[jorendumoulin]

is this https://github.com/pulp-platform/axi?

[rgantonio]

is this https://github.com/pulp-platform/axi?

Yes! According to Morritz, we have to use version 0.39.1.

We have this in our bender already. Then when PR #173 was made a month ago, it was meant for the CONVOLVE project. Then now it seems we need to add the switch who will use SNAX.

We found it was a versioning problem because @xiaoling-yi pointed out it builds on hers. Then when I checked it did build.

We won't use this lower bandwidth AXI for our internal tapeout. But, for other partners, they need to.

[rgantonio]

Also thank you!!! @jorendumoulin