Console Freezing Issue with CVA5 CPU

[Liamfeng]

Hello,

I am experiencing an issue when running the console with the CVA5 CPU using the script ./litex_sim.py --cpu-type cva5 --with-sdram. The console consistently freezes after typing just a few characters, without even pressing enter. On rare occasions, I can enter a full command, but this is uncommon.

I have isolated the problem to the litex_getc(FILE *file) function located in litex/litex/soc/software/libc/stdio.c. The program appears to get trapped in an infinite while loop within this function, preventing it from progressing.

In an effort to resolve this, I replaced the while loop with a for loop that iterates 1000 times, hoping that breaking out of the loop would stop the freezing. Unfortunately, the console still freezes after a few characters.

The screenshot below shows my console in a frozen state when running on the CVA5 CPU:

I also tested the script with the vexriscv_smp and vexriscv CPUs. Although the issue persists, I am able to type a lot more characters before the console freezes:

Could anyone help me resolve this issue or provide insight into what might be happening? Any assistance would be greatly appreciated. Thank you!

Environment:
CPU: CVA5 (also tested with vexriscv_smp and vexriscv)
Script: ./litex_sim.py --cpu-type cva5 --with-sdram
File: litex/litex/soc/software/libc/stdio.c
Function: litex_getc(FILE *file)

[enjoy-digital]

Hi @Liamfeng,

I haven't used personally CVA5 yet but if you want more visibility, in simulation it's possible to enable tracing signals to a waveform with --trace , this could allow you to better understand what the CPU is doing through the memory/peripheral accesses.