TinyUSB examples for Fomu fail under Renode simulation (jump to NULL in osal_queue_receive)

[sandip-mips]

Description

I am trying to run the TinyUSB device examples (cdc_msc/dfu) with the Fomu board configuration inside Renode. The simulation starts, but as soon as tud_task() is called, execution falls into the trap vector.

From GDB, I see that inside osal_queue_receive() the firmware tries to call qhdl->interrupt_set(false), but qhdl is NULL. That results in a jalr to 0x00000000 and execution ends up in trap_entry.

Additional information

Relevant frames from GDB:

0x20041098 <main+0x144>: jalr a5
# a5 loaded from 0(s0), but s0==0 → jump to 0

[*#0] 0x20041098 <main+0x144> (osal_queue_receive)
[ #1] 0x20041098 <tud_task_ext>
[ #2] 0x20041098 <tud_task>
[ #3] 0x20040104 <infinite_loop> (bss_done)

After single-step, $pc = 0x00000000

mcause shows Exception Code = 2 (illegal instruction), because execution at address 0 isn’t valid.

Any guidance on getting TinyUSB device examples working in Renode for Fomu?

[hathach]

does the example run on actual hardware, I tested with FOMU but that is a long time ago. Never tried with simulation

[sandip-mips]

No, I just tried on renode simulation.

[hathach]

maybe you can try to contact the simulation author/writer