Kernel hangs after enabling early printk

[hariprasath]

Dear all

We have a custom board based on imx6 running 3.10.17. We wanted to debug an issue during kernel boot-up. So we enabled Early printk & low level kernel debug option in the kernel configuration. But when we boot the kernel with these options enabled, we are able to see nothing after the 'Starting kernel...' print. This happens only after enabling these options. Any idea if some other configuration is missing associated with this ?

U-Boot 2013.04-eagle-imx6-gce0ea25-r1 (Apr 06 2015 - 12:55:55)

I2C:   ready

DRAM:  1 GiB

NAND:  2048 MiB

Using default environment

In:    serial

Out:   serial

Err:   serial

Normal Boot

Hit any key to stop autoboot:  0

NAND read: device 0 offset 0x800000, size 0x1000000

16777216 bytes read: OK

## Booting kernel from Legacy Image at 10007fc0 ...

   Image Name:   eagle-imx6-3.10.17(dt)

   Image Type:   ARM Linux Kernel Image (uncompressed)

   Data Size:    7848813 Bytes = 7.5 MiB

   Load Address: 10008000

   Entry Point:  10008000

   Verifying Checksum ... OK

   XIP Kernel Image ... OK

OK

Total milliseconds boot time: 751

Starting kernel ...

[hariprasath]

Looks like one of the config argument need to be updated manually to reflect the console UART to use and also the u-boot argument shown below should be added.

CONFIG_DEBUG_IMX_UART_PORT=4

Append "earlyprintk" in the boot arguments.

[jimmychan]

Please try this:

Embedded Buzz: ENABLING LOW LEVEL KERNEL DEBUGGING AND USING EARLY PRINTKs