Is it possible to add print in rocketchip?

[wasd003]

Type of issue: Question

Problem Description

I am a newbie to Rocketchip and I have been using Verilator to develop some custom features on Rocketchip. During my development process, I usually rely on waveform debugging to identify bugs. However, I have encountered a problem that only occurs when the emulator is not in debug mode. Unfortunately, generating waveforms is only possible when the emulator is compiled in debug mode.

To address this bug, I would like to know if there is a way to add print statements in Rocketchip's Chisel code.

What I have tried

I have tried to add printf in CSR.scala directly but no luck. I have also noticed that there are some existing printf statements in RocketCore.scala which look like:

printf("C%d: %d [%d] pc=[%x] W[r%d=%x][%d] R[r%d=%x] R[r%d=%x] inst=[%x] DASM(%x)\n",                                                                                                                                                                                             
   io.hartid, coreMonitorBundle.timer, coreMonitorBundle.valid,                                                                                                                                                                                                                   
   coreMonitorBundle.pc,                                                                                                                                                                                                                                                          
   Mux(wb_ctrl.wxd || wb_ctrl.wfd, coreMonitorBundle.wrdst, 0.U),                                                                                                                                                                                                                 
   Mux(coreMonitorBundle.wrenx, coreMonitorBundle.wrdata, 0.U),                                                                                                                                                                                                                   
   coreMonitorBundle.wrenx,                                                                                                                                                                                                                                                       
   Mux(wb_ctrl.rxs1 || wb_ctrl.rfs1, coreMonitorBundle.rd0src, 0.U),                                                                                                                                                                                                              
   Mux(wb_ctrl.rxs1 || wb_ctrl.rfs1, coreMonitorBundle.rd0val, 0.U),                                                                                                                                                                                                              
   Mux(wb_ctrl.rxs2 || wb_ctrl.rfs2, coreMonitorBundle.rd1src, 0.U),                                                                                                                                                                                                              
   Mux(wb_ctrl.rxs2 || wb_ctrl.rfs2, coreMonitorBundle.rd1val, 0.U),                                                                                                                                                                                                              
   coreMonitorBundle.inst, coreMonitorBundle.inst)                                                                                                                                                                                                                                
} 

It seems that output of the executed assembly tests under emulator/output/*.out is generated here. However when I delete these print statements, those logs can still be generated. This makes me unsure if the printf in Rocketore.scala is actually working.

Command I use

./emulator-freechips.rocketchip.system-freechips.rocketchip.system.DefaultConfig +max-cycles=100000000 +verbose output/cvm.riscv 3>&1 1>&2 2>&3 | /opt/riscv/bin/spike-dasm  > output/cvm.riscv.out

Environment

RocketChip Commit: 25e2c63567689ebe1fc5e60fdfe3375a8dba071c
Host Linux version: 5.19.0-45-generic #46~22.04.1-Ubuntu SMP PREEMPT_DYNAMIC Wed Jun 7 15:06:04 UTC 20 x86_64 x86_64 x86_64 GNU/Linux
sbt version: 1.8.3

Thanks for your attention to this matter. Any reply will be highly appreciated.

[ZenithalHourlyRate]

However when I delete these print statements, those logs can still be generated. This makes me unsure if the printf in Rocketore.scala is actually working.

You might have encountered building cache issues. You might get a clean environment, delete the printf and build the emulator again.

if there is a way to add print statements in Rocketchip's Chisel code.

The snippet you show is exactly the way to add printf, and it will become effective by +verbose of the emulator and then get redirected to your output/cvm.riscv.out