[Techtalk] ttyS1: LSR safety check engaged!

[Carla Schroder]

On Wednesday 07 September 2005 8:56 pm, agoats wrote:
> > Simple question- wot the heck does 'ttyS1: LSR safety check engaged!'
> > mean? It's dmesg output. I have Googled, and found only other puzzled
> > souls.
> >

>
> This one's obscure enough I'm going to jump in early... no offense!
>
> All of the LSR instructions are buried in the serial driver source code
> for the kernel source.
>
> /usr/src/linux/drivers/char/serial.c

Thanks, I don't mind digging through obsure docs when I'm in the mood. :)

The amusing bit is on this particular PC there is only one serial port & UART, 
on ttyS0. This is what setserial shows:

$ setserial -g /dev/ttyS[0123]
/dev/ttyS0, UART: 16550A, Port: 0x03f8, IRQ: 4
/dev/ttyS1: No such device
/dev/ttyS2, UART: unknown, Port: 0x03e8, IRQ: 4
/dev/ttyS3, UART: unknown, Port: 0x02e8, IRQ: 3

$ setserial -a /dev/ttyS0
/dev/ttyS0, Line 0, UART: 16550A, Port: 0x03f8, IRQ: 4
        Baud_base: 115200, close_delay: 50, divisor: 0
        closing_wait: 3000
        Flags: spd_normal skip_test

$ setserial -a /dev/ttyS1
/dev/ttyS1: No such device

$ setserial -a /dev/ttyS2
/dev/ttyS2, Line 2, UART: unknown, Port: 0x03e8, IRQ: 4
        Baud_base: 115200, close_delay: 50, divisor: 0
        closing_wait: 3000
        Flags: spd_normal skip_test

Weird, huh. S3 & 4 should also return "No such device." Mysterious are the 
ways of the Linux kernel.

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