I have a custom am572x board which is similar but not identical to the am57xx_evm. I am using sdk version: sdk-linux-am57xx-evm-02.00.02.11
I have modified the u-boot image and am booting to the u-boot prompt.
I have modified the device tree to reduce the memory size down to the 256Mbyte of memory we have on our board. I have disabled many sections in the device tree that do not apply: video, sound, GPIO we don't use, and all of the other onboard processors except for 1 dsp. I have successfully compiled the .dts file to a .dtb file and have it in the /tftpboot/ dir, along with the TI prebuilt Zimae-am57xx-evm.bin
I try to boot linux using: run netboot , but it always fails after loading and jumping to the kernel.
my uboot code successfully loads the kernel to 0x82000000 and the device tree to 0x88000000 it then prints the following:
## Transferring control to Linux (at address 82000000)...
Starting kernel ...
## Done with 'announce_and_cleanup) (I added this debug message)
## jumping to 'kernel_entry' (I added this debug message just prior to the jump to the kernel)
The problem is, it hangs after jumping to the kernel and I need to figure out how to debug it. I was trying to use some bootargs to enable debug printing in the kernel, including earlyprintk, but so far nothing has printed out on the serial port after it hangs as shown above.
The way I tried to enable earlyprintk was through the 'optargs' provided by env var: netargs
netargs=setenv bootargs console=${console} ${optargs} root=/dev/nfs nfsroot=${serverip}:${rootpath},${nfsopts} rw ip=dhcp
so I created the following env variable:
tftpargs=setenv optargs debug earlyprintk=ttyO2,115200n8,keep loglevel=7 log_buf_len=16000 initcall_debug time
then I executed: run tftpargs
prior to executing: run netboot.
Questions:
1) did I correctly initialize 'earlyprintk'? if so, why didn't I get any debug output? Do I need to do something else?
2) Notice I also changed the debug loglevel to 7. Is this correct too?
3) Is there something I am missing that I need to do to see debug printouts as the kernel tries to boot?
4) is there a better way to debug this? as I am at a standstill now.