Fix AXI4 Xbar elaboration error due to missing fields

[tymcauley]

Related issue: #3548

Type of change: bug report

Impact: no functional change

Development Phase: implementation

Release Notes

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: tymcauley / name: Tynan McAuley (2a3bd4e)

[jerryz123]

Can you rebase this PR on dev?

[tymcauley]

Unfortunately I need to wait a bit to get some feedback from my company on the CLA, so resolving that is going to take some time.

[tymcauley]

On a recent firtool version (1.58.0), I found that I'm getting this error:

generators/rocket-chip/src/main/scala/amba/axi4/Xbar.scala:86:18: error: sink "in_1_w_bits_user_corrupt" not fully initialized in "AXI4Xbar"

I worked around it by adding this line right above the in(i).squeezeAll.waiveAll :<>= io_in(i).squeezeAll.waiveAll statement:

in(i).w.bits.user := DontCare

Not completely sure what the more principled way to solve this is, but I do see that tilelink/Xbar.scala also tying off some the user signals. Presumably we want user signals to propagate through the crossbar when appropriate.

[tymcauley]

Okay, I believe I've taken care of all the fields that need to be tied off in case they're not used by a particular destination.

[tymcauley]

Checking on the status of this, anything else that I need to do before this can be merged @jerryz123 ?

[jerryz123]

Nope, this just slipped past me. Let's merge this

[tymcauley]

Nope, this just slipped past me. Let's merge this

Thanks so much!