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hello to everybody I have Ubuntu Lucid 10.04 installed on my Desktop and I have a PCI serial card in my computer and it has only one serial port. Actually ...
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  1. #1
    Just Joined!
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    Jun 2010
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    6

    /dev/ttyS0: Device or resource busy


    hello to everybody

    I have Ubuntu Lucid 10.04 installed on my Desktop and I have a PCI serial card in my computer and it has only one serial port.

    Actually I want to use this serial port for the serial communication and for that I executed this command :

    $ setserial -g /dev/ttyS[0123]

    and I got this as output:

    /dev/ttyS0: Device or resource busy
    /dev/ttyS1, UART: undefined, Port: 0xee00, IRQ: 16
    /dev/ttyS2, UART: undefined, Port: 0xed00, IRQ: 17
    /dev/ttyS3, UART: unknown, Port: 0xec00, IRQ: 17

    in this it is showing that my serisl port named /dev/ttyS0 is busy and can't be used for the serial communication.

    But it is happening from past couple of days, and before that everything was just fine and on the execution of the previous command it was giving this as output:

    /dev/ttyS0, UART: undefined, Port: 0xef00, IRQ: 16
    /dev/ttyS1, UART: undefined, Port: 0xee00, IRQ: 16
    /dev/ttyS2, UART: undefined, Port: 0xed00, IRQ: 17
    /dev/ttyS3, UART: unknown, Port: 0xec00, IRQ: 17


    So now what is this happening ...........................


    I also googled a lot and got various hints but nothing worked well , and I tried to know whether the interrupt no. 16 being used by some other device than for that I checked the /proc/interrupts file and got the following result:

    CPU0 CPU1
    0: 69 0 IO-APIC-edge timer
    1: 43 5783 IO-APIC-edge i8042
    8: 1 0 IO-APIC-edge rtc0
    9: 0 0 IO-APIC-fasteoi acpi
    12: 455224 0 IO-APIC-edge i8042
    14: 0 0 IO-APIC-edge ata_piix
    15: 0 0 IO-APIC-edge ata_piix
    16: 891 121426 IO-APIC-fasteoi uhci_hcd:usb5, i915, HDA Intel, serial
    17: 4 0 IO-APIC-fasteoi
    18: 0 0 IO-APIC-fasteoi uhci_hcd:usb4
    19: 149907 0 IO-APIC-fasteoi ata_piix, uhci_hcd:usb3
    20: 56 49397 IO-APIC-fasteoi ohci1394, eth0
    23: 478297 0 IO-APIC-fasteoi ehci_hcd:usb1, uhci_hcd:usb2
    NMI: 0 0 Non-maskable interrupts
    LOC: 1844145 1720957 Local timer interrupts
    SPU: 0 0 Spurious interrupts
    PMI: 0 0 Performance monitoring interrupts
    PND: 0 0 Performance pending work
    RES: 74493 98624 Rescheduling interrupts
    CAL: 90 128 Function call interrupts
    TLB: 7221 7432 TLB shootdowns
    TRM: 0 0 Thermal event interrupts
    THR: 0 0 Threshold APIC interrupts
    MCE: 0 0 Machine check exceptions
    MCP: 23 23 Machine check polls
    ERR: 1
    MIS: 0
    ~
    ~
    ~
    ~

    In this file I saw that the serial port and the Intel HDA both are using the same interrupt no 16 and therefore I think the serial port is not responding or is busy.

    I checked the other serial port /dev/ttyS1 with the same IRQ 16 and executed this command :

    $ setserial /dev/ttyS1 -a

    and got the following result:

    /dev/ttyS1, Line 1, UART: undefined, Port: 0xee00, IRQ: 16
    Baud_base: 115200, close_delay: 50, divisor: 0
    closing_wait: 3000
    Flags: spd_normal skip_test



    So this was free and I tried to use it.
    So I tried to switch over to other serial port by running the following command:

    $ setserial /dev/ttyS1 uart 16550A
    $ setserial /dev/ttyS1 -a

    and the result was this:

    /dev/ttyS1, Line 1, UART: 16550A, Port: 0xee00, IRQ: 16
    Baud_base: 115200, close_delay: 50, divisor: 0
    closing_wait: 3000
    Flags: spd_normal skip_test

    So I tried to use it and when I did this the system gets shutdown.


    I tried this with the other two ports also but got nothing working and the system shuts down in each case and the result obtained all the time was same :

    $ setserial /dev/ttyS0 -a
    /dev/ttyS0: Device or resource busy

    So I want to know how I can troubleshoot this problem .......please help me out of this .


    Thank you

  2. #2
    Linux User
    Join Date
    Nov 2008
    Location
    Tokyo, Japan
    Posts
    260
    You PCI Serial card may be using a different set of IRQ's for the serial ports. It is possible that the serial ports for this card are configured with different symbols in the "/dev" directory. You should refer to the instructions given by the manufacturer of the card.

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