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get log from kernel with only usb-connection

alexey ivannikov
Prodigy 20 points
Other Parts Discussed in Thread: OMAPL138

There is a am35xx-based device without ethernet, uart ports. It has usb connection with host, numeric keyaboard, lcd display. There is working uboot and kernle images for this. I'm trying to made some little changes in linux kernel and deploy but there is some problem while kernel is loading and i can't receive any information while kernel is loading. May somebody suggest what steps are needed to receive this information.

  • 0
    TI__Guru** 116100 points

    Hi.

    Yes it is possible.

    1) Need "USB to Serial" converter cable for getting the /dev/ttyUSBx node.

    2) Enable USB to serial support in linux as follows.

    make menuconfig ARCH=arm CROSS_COMPILE=arm-arago-linux-gnueabi-

    Device Drivers  --->
    [*] USB support  --->
        <*>   USB Modem (CDC ACM) support
        <*>   USB Serial Converter support  --->
            [*]   USB Serial Console device support
            [*]   USB Generic Serial Driver
            <*>   USB FTDI Single Port Serial Driver
            <*>   USB Prolific 2303 Single Port Serial Driver

    3) Change the /etc/inittab file in filesystem to login "/dev/ttyUSB0" as follows.

    Ex:

    S:2345:respawn:/sbin/getty 115200 ttyS2

    TO

    S:2345:respawn:/sbin/getty 115200 ttyUSB0

    4) Change the bootargs.

     setenv bootargs mem=32M console=/dev/ttyS2,115200 ip=dhcp nfsroot=10.100.1.72:/usr/local/filesystem_omapl138 root=/dev/nfs
     rw rootwait

    TO

     setenv bootargs mem=32M console=/dev/ttyUSB0,115200 ip=dhcp nfsroot=10.100.1.72:/usr/local/filesystem_omapl138 root=/dev/nfs
     rw rootwait

    PFA of log.

    0576.log_ttyUSB0.txt

    I hope it helps.

  • 0 in reply to Titusrathinaraj Stalin
    Prodigy 20 points

    Hello. Thanks for answer. I can't exactly understand what do you suggest. The device doesn't have serial port, it has only USB port. Do you mean this connection : USB device - COM host ?

  • 0 in reply to alexey ivannikov
    TI__Guru** 116100 points

    Hi,

    Hello. Thanks for answer. I can't exactly understand what do you suggest. The device doesn't have serial port, it has only USB port. Do you mean this connection : USB device - COM host ?

    Yes.

    Connect "USB to serial" converter (prolific or FTDI) cable to your device USB port,

    You can get kernel logs from the ttyUSB0 node which is detected from  "USB to serial" converter.

    Got it !