[U-Boot] COM port tracing

MattS zzebowa at hotmail.com
Thu Sep 5 15:10:30 UTC 2019

Hi all

I am new at this, so excuse my ignorance, but I have been playing with
u-boot and have hit a bit of a wall with loading the kernel. 

The u-boot and kernel are compiled for PPC.  The kernel is mkimaged to a

i am loading it to RAM  with tftp, and running it with bootm <addr>.

Up to the point where it 'Transfers to Linux', everything looks OK, but
after that I get no more tracing.

mpc8313> bootm  0x01000000
## Current stack ends at 0x0ff01be0
*  kernel: cmdline image address = 0x01000000
## Booting kernel from Legacy Image at 01000000 ...
   Image Name:
   Image Type:   PowerPC Linux Kernel Image (uncompressed)
   Data Size:    6348856 Bytes = 6.1 MiB
   Load Address: 00000000
   Entry Point:  00000000
   Verifying Checksum ... OK
   kernel data at 0x01000040, len = 0x0060e038 (6348856)
## No init Ramdisk
   ramdisk start = 0x00000000, ramdisk end = 0x00000000
## No Flattened Device Tree
Continuing to boot without FDT
Initial value for argc=3
Final value for argc=3
   Loading Kernel Image ... OK
   kernel loaded at 0x00000000, end = 0x0060e038
## initrd_high = 0x10000000, copy_to_ram = 1
   ramdisk load start = 0x00000000, ramdisk load end = 0x00000000
Initial value for argc=3
Final value for argc=3
Initial value for argc=3
Final value for argc=3
## cmdline at 0x0ff007e0 ... 0x0ff007fc
## kernel board info at 0x0ff00790
bd address  = 0x0ff01fb0
memstart    = 0x00000000
memsize     = 0x10000000
flashstart  = 0xfc000000
flashsize   = 0x04000000
flashoffset = 0x00000000
sramstart   = 0x00000000
sramsize    = 0x00000000
bootflags   = 0x00000000
intfreq     = 333.333 MHz
busfreq     = 133.333 MHz
ethaddr     = 00:D1:11:A4:03:37
eth1addr    = (not set)
IP addr     =
baudrate    = 115200 bps
relocaddr   = 0x0ff84000
## cmdline at 0x0ff00390 ... 0x0ff003ac
## Transferring control to Linux (at address 00000000) ...
   Booting using board info...

Is this  Linux failing to run, or Linux failing to trace?

Also, do I need to create a separate FDT or does the kernel compile with one
built in (I dont see a specific option to control this in the kernel

Thanks in advance for any help here.

Sent from: http://u-boot.10912.n7.nabble.com/

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