How many serial ports will work on Ubuntu?

[Dotan Cohen]

A neighbour's computer has five serial ports, one on the motherboard
and four on a PCI card. However, only four cards are showing:

# dmesg | grep tty
[    0.000000] console [tty0] enabled
[    0.394565] serial8250: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
[    0.394877] 00:08: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
[    0.395080] 0000:03:06.0: ttyS1 at I/O 0xcf00 (irq = 20) is a 16550A
[    0.395201] 0000:03:06.0: ttyS2 at I/O 0xce00 (irq = 20) is a 16550A
[    0.395320] 0000:03:06.0: ttyS3 at I/O 0xcd00 (irq = 20) is a 16550A
[    8.751992] setserial sets custom speed on ttyS1. This is deprecated.
[    8.754670] setserial sets custom speed on ttyS3. This is deprecated.
[   70.056749] redhot sets custom speed on ttyS3. This is deprecated.
[   80.734705] radoga sets custom speed on ttyS1. This is deprecated.
[ 5437.884113] redhot sets custom speed on ttyS3. This is deprecated.
[ 5510.465311] redhot sets custom speed on ttyS3. This is deprecated.
[ 5662.096348] redhot sets custom speed on ttyS3. This is deprecated.
[ 5692.931148] redhot sets custom speed on ttyS3. This is deprecated.
#

The motherboard card is ttys0. All five ports work in Windows, and
replacing the PCI card with another identical, known good card showed
the same results. This is Ubuntu 10.04. Is Ubuntu limited to only four
serial ports? Thanks.

--
Dotan Cohen

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