Memory initialization failed,(PicoRV32,FemtoRV-STANDARD) on digilent_cmod_a7 board

[Sudlor]

Both PicoRV32 and FemetoRV-STANDARD cant upload by this command litex_term /dev/ttyUSB1 --kernel=demo.bin. It said

  Write: 0x40000000-0x40080000 512.0KiB   
   Read: 0x40000000-0x40080000 512.0KiB   
  bus errors:  0/256
  addr errors: 0/8192
  data errors: 131072/131072
Memtest KO
Memspeed at 0x40000000 (Sequential, 512.0KiB)...
  Write speed: 13.0MiB/s
   Read speed: 18.3MiB/s
Memory initialization failed

what I have do if I want to upload demo on picorv32 cpu and femetorv cpu?
please tell me the solution.
however,when I try on vexriscv cpu, it works just fine. I can call the donut.

PS.I used digilent_cmod_a7 board