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    SubjectRe: Bogus serial port ttyS02
    On Wed, 13 Aug 2003, Geert Uytterhoeven wrote:

    >
    > Linux always finds 3 serial ports instead of 2:
    >
    > | ttyS00 at 0x03f8 (irq = 4) is a 16550A
    > | ttyS01 at 0x02f8 (irq = 3) is a 16550A
    > | ttyS02 at 0x03e8 (irq = 4) is a 16450
    >
    > The last one is bogus.

    First, this looks like ix86 stuff, not m68k. Drivers for ix86
    machines probe the de facto addresses for up to a maximum of
    4 8250-type UARTS. Those addresses are:

    (0) 0x3f8
    (1) 0x2f8
    (2) 0x3e8
    (3) 0x328

    (from the Phoenix SYSTEM BIOS book)

    Usually, there are several bits that are permanently 0 in
    some of the registers. This is used to "positively" identify
    the chip. Note that many IR devices are also connected
    to 8250-type UARTS.

    I would guess that you have two serial ports, plus another
    UART that's used for IR (maybe a IR keyboard???).

    You can do `od /dev/ttyS2` from the root account and see
    what happends.


    Cheers,
    Dick Johnson
    Penguin : Linux version 2.4.20 on an i686 machine (797.90 BogoMips).
    Note 96.31% of all statistics are fiction.

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