Beaglebone Black : Could not display u-boot prompt

Question

I'm studying with a Mastering Embedded Linux Programming second edition

can't see the u-boot prompt (U-Boot#)

I used u-boot v2020.07, crosstool-ng v1.24.0 and copied MLO, u-boot.img to sd card.

How can I solve this problem?

thanks.

U-Boot SPL 2020.07 (Oct 21 2020 - 13:46:52 +0900)
Trying to boot from MMC1

U-Boot 2020.07 (Oct 21 2020 - 13:46:52 +0900)

CPU  : AM335X-GP rev 2.1
Model: TI AM335x BeagleBone Black
DRAM:  512 MiB
WDT:   Started with servicing (60s timeout)
NAND:  0 MiB
MMC:   OMAP SD/MMC: 0, OMAP SD/MMC: 1
Loading Environment from FAT... *** Warning - bad CRC, using default environment

<ethaddr> not set. Validating first E-fuse MAC
Net:   eth0: ethernet@4a100000
Warning: usb_ether MAC addresses don't match:
Address in ROM is       de:ad:be:ef:00:01
Address in environment is   d0:5f:b8:d1:0b:69
, eth1: usb_ether
Hit any key to stop autoboot:  0 
switch to partitions #0, OK

mmc0 is current device
SD/MMC found on device 0
switch to partitions #0, OK

mmc0 is current device
Scanning mmc 0:1...
switch to partitions #0, OK

mmc0 is current device
SD/MMC found on device 0
switch to partitions #0, OK

mmc1(part 0) is current device
Scanning mmc 1:1...
switch to partitions #0, OK

mmc1(part 0) is current device
SD/MMC found on device 1
Error: "bootcmd_nand0" not defined

starting USB...
Bus usb@47401800: Port not available.
ethernet@4a100000 Waiting for PHY auto negotiation to complete......... TIMEOUT !

using musb-hdrc, OUT ep1out IN ep1in STATUS ep2in
MAC de:ad:be:ef:00:01
HOST MAC de:ad:be:ef:00:00
RNDIS ready

missing environment variable: pxeuuid
Retrieving file: pxelinux.cfg/01-d0-5f-b8-d1-0b-67
ethernet@4a100000 Waiting for PHY auto negotiation to complete......... TIMEOUT !

Warning: usb_ether MAC addresses don't match:
Address in ROM is       de:ad:be:ef:00:01
Address in environment is   d0:5f:b8:d1:0b:69
using musb-hdrc, OUT ep1out IN ep1in STATUS ep2in
MAC de:ad:be:ef:00:01
HOST MAC de:ad:be:ef:00:00
RNDIS ready
Retrieving file: pxelinux.cfg/00000000
ethernet@4a100000 Waiting for PHY auto negotiation to complete......... TIMEOUT !

Warning: usb_ether MAC addresses don't match:
Address in ROM is       de:ad:be:ef:00:01
Address in environment is   d0:5f:b8:d1:0b:69
using musb-hdrc, OUT ep1out IN ep1in STATUS ep2in
MAC de:ad:be:ef:00:01
HOST MAC de:ad:be:ef:00:00
RNDIS ready
Retrieving file: pxelinux.cfg/0000000
ethernet@4a100000 Waiting for PHY auto negotiation to complete......... TIMEOUT !

Warning: usb_ether MAC addresses don't match:
Address in ROM is       de:ad:be:ef:00:01
Address in environment is   d0:5f:b8:d1:0b:69
using musb-hdrc, OUT ep1out IN ep1in STATUS ep2in
MAC de:ad:be:ef:00:01
HOST MAC de:ad:be:ef:00:00
RNDIS ready
Retrieving file: pxelinux.cfg/000000
ethernet@4a100000 Waiting for PHY auto negotiation to complete......... TIMEOUT !

Warning: usb_ether MAC addresses don't match:
Address in ROM is       de:ad:be:ef:00:01
Address in environment is   d0:5f:b8:d1:0b:69
using musb-hdrc, OUT ep1out IN ep1in STATUS ep2in
MAC de:ad:be:ef:00:01
HOST MAC de:ad:be:ef:00:00
RNDIS ready
Retrieving file: pxelinux.cfg/00000
ethernet@4a100000 Waiting for PHY auto negotiation to complete......... TIMEOUT !

Warning: usb_ether MAC addresses don't match:
Address in ROM is       de:ad:be:ef:00:01
Address in environment is   d0:5f:b8:d1:0b:69
using musb-hdrc, OUT ep1out IN ep1in STATUS ep2in
MAC de:ad:be:ef:00:01
HOST MAC de:ad:be:ef:00:00
RNDIS ready
Retrieving file: pxelinux.cfg/0000
ethernet@4a100000 Waiting for PHY auto negotiation to complete......... TIMEOUT !

Warning: usb_ether MAC addresses don't match:
Address in ROM is       de:ad:be:ef:00:01
Address in environment is   d0:5f:b8:d1:0b:69
using musb-hdrc, OUT ep1out IN ep1in STATUS ep2in
MAC de:ad:be:ef:00:01
HOST MAC de:ad:be:ef:00:00
RNDIS ready
Retrieving file: pxelinux.cfg/000
ethernet@4a100000 Waiting for PHY auto negotiation to complete......... TIMEOUT !

Warning: usb_ether MAC addresses don't match:
Address in ROM is       de:ad:be:ef:00:01
Address in environment is   d0:5f:b8:d1:0b:69
using musb-hdrc, OUT ep1out IN ep1in STATUS ep2in
MAC de:ad:be:ef:00:01
HOST MAC de:ad:be:ef:00:00
RNDIS ready
Retrieving file: pxelinux.cfg/00
ethernet@4a100000 Waiting for PHY auto negotiation to complete......... TIMEOUT !

Warning: usb_ether MAC addresses don't match:
Address in ROM is       de:ad:be:ef:00:01
Address in environment is   d0:5f:b8:d1:0b:69
using musb-hdrc, OUT ep1out IN ep1in STATUS ep2in
MAC de:ad:be:ef:00:01
HOST MAC de:ad:be:ef:00:00
RNDIS ready
Retrieving file: pxelinux.cfg/0
ethernet@4a100000 Waiting for PHY auto negotiation to complete......... TIMEOUT !

Warning: usb_ether MAC addresses don't match:
Address in ROM is       de:ad:be:ef:00:01
Address in environment is   d0:5f:b8:d1:0b:69
using musb-hdrc, OUT ep1out IN ep1in STATUS ep2in
MAC de:ad:be:ef:00:01
HOST MAC de:ad:be:ef:00:00
RNDIS ready
Retrieving file: pxelinux.cfg/default-arm-am33xx-am335x
ethernet@4a100000 Waiting for PHY auto negotiation to complete......... TIMEOUT !

Warning: usb_ether MAC addresses don't match:
Address in ROM is       de:ad:be:ef:00:01
Address in environment is   d0:5f:b8:d1:0b:69
using musb-hdrc, OUT ep1out IN ep1in STATUS ep2in
MAC de:ad:be:ef:00:01
HOST MAC de:ad:be:ef:00:00
RNDIS ready
Retrieving file: pxelinux.cfg/default-arm-am33xx
ethernet@4a100000 Waiting for PHY auto negotiation to complete......... TIMEOUT !

Warning: usb_ether MAC addresses don't match:
Address in ROM is       de:ad:be:ef:00:01
Address in environment is   d0:5f:b8:d1:0b:69
using musb-hdrc, OUT ep1out IN ep1in STATUS ep2in
MAC de:ad:be:ef:00:01
HOST MAC de:ad:be:ef:00:00
RNDIS ready
Retrieving file: pxelinux.cfg/default-arm
ethernet@4a100000 Waiting for PHY auto negotiation to complete......... TIMEOUT !

Warning: usb_ether MAC addresses don't match:
Address in ROM is       de:ad:be:ef:00:01
Address in environment is   d0:5f:b8:d1:0b:69
using musb-hdrc, OUT ep1out IN ep1in STATUS ep2in
MAC de:ad:be:ef:00:01
HOST MAC de:ad:be:ef:00:00
RNDIS ready
Retrieving file: pxelinux.cfg/default
ethernet@4a100000 Waiting for PHY auto negotiation to complete......... TIMEOUT !

Warning: usb_ether MAC addresses don't match:
Address in ROM is       de:ad:be:ef:00:01
Address in environment is   d0:5f:b8:d1:0b:69
using musb-hdrc, OUT ep1out IN ep1in STATUS ep2in
MAC de:ad:be:ef:00:01
HOST MAC de:ad:be:ef:00:00
RNDIS ready
Config file not found
starting USB...
Bus usb@47401800: Port not available.
ethernet@4a100000 Waiting for PHY auto negotiation to complete......... TIMEOUT !

Warning: usb_ether MAC addresses don't match:
Address in ROM is       de:ad:be:ef:00:01
Address in environment is   d0:5f:b8:d1:0b:69
using musb-hdrc, OUT ep1out IN ep1in STATUS ep2in
MAC de:ad:be:ef:00:01
HOST MAC de:ad:be:ef:00:00
RNDIS ready
ethernet@4a100000 Waiting for PHY auto negotiation to complete......... TIMEOUT !

Warning: usb_ether MAC addresses don't match:
Address in ROM is       de:ad:be:ef:00:01
Address in environment is   d0:5f:b8:d1:0b:69
using musb-hdrc, OUT ep1out IN ep1in STATUS ep2in
MAC de:ad:be:ef:00:01
HOST MAC de:ad:be:ef:00:00
RNDIS ready


=> 

Answer 1

This may be that the prompt you are getting is the the one you were expecting, but you definitively got a prompt from u-boot, i.e. the final => in the output you posted.

If you enter help then press enter, you should get the list of available commands.

This book is five years old now, and you are using u-boot 2020.07, this may explain the discrepancy.

The author may have customized the prompt message in the u-boot he compiled as well: you can do the same by adding a adding/modifying the value in the CONFIG_SYS_PROMPT symbol definition in the configuration file you used, say configs/am335x_evm_defconfig

CONFIG_SYS_PROMPT="U-Boot# "

After having re-compiled u-boot, you should get the exact prompt message you were expecting.