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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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