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Newbie: no Linux kernel output on serial

Tapani
Prodigy 100 points
Other Parts Discussed in Thread: DM3730

Hello,

just started playing around with an OMAP dm3730, and I cannot get any kernel output on the serial console using a recent kernel.

U-boot interaction works fine, and the last thing I see is

"Starting kernel ..."

and nothing more. I expect to see the "Uncompressing Linux..." printout.

I have tried setting both the console and earlycon parameters to ttyO2,115200n8 in both u-boot and in kernel config. I have early printk enabled (if that is needed).

 

I have a v2.6.32 kernel where everything works as it should, so my setup is ok. I have tried with both v2.9.39 and 3.0.0-rc7 without luck, and tried to reconfigure my kernel from scratch and to port the oldconfig to the current kernel.

Any ideas on what would prevent the printout?  I am suspecting some little setting in the kernel, but it is a needle in a haystack to find out.. and my knowledge of the area is limited.

 

thank you in advance,

//T

  • 0
    Expert 1205 points

    Hi Tapani,

             Can you please post the bootargs you've used?

              I reckon you have to be using:

              setenv console=ttyO0,115200n8

              Please try the same and post your log.

     

    Regards,

    N.S.SriHarsha

  • 0 in reply to SriHarsha N.S
    TI__Expert 3990 points

    Hi Tapani,

     

    I have been using these bootargs for my beagle-xm and it works fine for me:

    console=ttyS2,115200n8 root=/dev/mmcblk0p2 noinitrd rw ip=off mem=512M@0x80000000 vram=20M omapfb.vram=0:20M omap_vout.vid1_static_vrfb_alloc=y omapfb.mode=dvi:1280x720@60 omapdss.def_disp=dvi rootdelay=1

    Let me know if this works for you.

  • 0 in reply to Anuj Aggarwal
    Prodigy 100 points

    N.S.SriHarsha,

    thank you for your answer. The problem is likely not in the console bootarg; even if it is wrong you get to see the "Uncompressing Linux ..." line (but nothing after that). Tried it on my working 2.6.32 :-)

     

    Anuj,

    no - those bootargs do not work for me. Got my hands on on a beagleboard xM, so I was able to test on the same hardware. Are you sure those are correct? As far as I know, the serial is renamed to ttyOx, while your console is set to ttyS2, which is the device name used years ago.

    My strong suspicion is towards my kernel configuration: as I said, the included 2.6.32 kernel works (for both the dm3730 board and Beagleboard xM), and I can recompile (reconfigured and/or modified) 2.6.32 kernels without problems. Reconfiguring or "make oldconfig"-ing for, say, 2.6.39 results in no kernel output.

    Could you somehow send me your Beagleboard xM kernel configuration?

    regards,

    Tapani

     

  • 0 in reply to Tapani
    Prodigy 100 points

    Problem solved.

    I was able to find a working beagleboard xm kernel with a working configuration. Using the beagleboard config, I could add my settings to the .config, and get kernel output from my dm3730. I still do not know which kernel option I was missing, but it was not the boot args.

    Thank you for the hint about beagleboard xm.