Support custom bundles in Trace

[jerryz123]

An alternative approach to #3355, core implementations can set a custom traceCustom field to pull out extra information out of the TraceBundle.

@bgottschall does this look OK for you?

Related issue:

Type of change: other enhancement

Impact: API addition (no impact on existing code)

Development Phase: implementation

Release Notes

[jerryz123]

@ZenithalHourlyRate @sequencer the CI machines do not provide logs, and the mill flow on dev fails for me with

[5/140] mill.scalalib.ZincWorkerModule.worker 
1 targets failed
mill.scalalib.ZincWorkerModule.worker java.lang.ClassNotFoundException: mill.scalalib.worker.ZincWorkerImpl
    java.base/java.net.URLClassLoader.findClass(URLClassLoader.java:476)
    mill.api.ClassLoader$$anon$1.findClass(ClassLoader.scala:47)
    java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:589)
    java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:522)
    mill.scalalib.ZincWorkerModule.$anonfun$worker$3(ZincWorkerModule.scala:58)
make: *** [/nscratch/jerryz/chipyard-proj/rocket-chip/Makefrag:47: /nscratch/jerryz/c

[bgottschall]

@bgottschall does this look OK for you?

Yes, that looks good!

[sequencer]

Interesting, I'll debug it tomorrow.

[sequencer]

I have two concerns, both these are not problem in the near future, and won't block this PR:

• Data cannot be serialized, although this is a common issue in most of Chisel designs, but I think we should eventually get rid of this in the user API of rocket-chip. user can use json to config their IP, rather than CDE.
• Trace has two design purpose: one for riscv-trace-spec, one for firesim-like debug. I personally think the later one is a part of verification and should be implemented with XMR.

[jerryz123]

• Data cannot be serialized, although this is a common issue in most of Chisel designs, but I think we should eventually get rid of this in the user API of rocket-chip. user can use json to config their IP, rather than CDE.

traceCustom doesn't have to be a user API, it is a source API, to allow other implementations of Tile to provide more information through that port. If a user wants to add more signals to that, then they have to edit source code to drive those signals from within the core anyways.

• Trace has two design purpose: one for riscv-trace-spec, one for firesim-like debug. I personally think the later one is a part of verification and should be implemented with XMR.

Unfortunately firesim does not support XMR yet

[jerryz123]

@Mergifyio backport master

[mergify]

backport master

✅ Backports have been created

Details

• #3359 Support custom bundles in Trace (backport #3356) has been created for branch master