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From: miquels@cistron.nl (Miquel van Smoorenburg)
Subject: Re: Serial Console
Date: 5 Dec 2000 17:00:06 GMT
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In article <200012051625.RAA02860@cave.bitwizard.nl>,
Rogier Wolff <R.E.Wolff@BitWizard.nl> wrote:
>Paul Jakma wrote:
>> perhaps linux-mips is just different? or i386 serial-console is
>> incorrect?
>
>No. serial console on i386 doesn't and should not block. 
>We're constantly using serial consoles here, so I really think I've 
>seen this work... .

It can block.

Funny, no message on this list has been quite right ;)

/dev/console can block
/dev/ttyS0   can block
printk()     never blocks

init(8) reads the tty settings from /etc/ioctl.save at startup.
After it leaves single user mode it writes that file again. So
mods made in single user mode are saved to /etc/ioctl.save.
Every time init executes a program, it restores the console
settings to those from /etc/ioctl.save.
[Perhaps I should rip that stuff out]

However a getty on /dev/ttyS0 which you usually have running in
runlevels [12345789] can change the tty settings and they will
take effect immidiately. So if you run a getty that turns on
hardware handshaking (like mgetty) - you're fscked.

The only things in which /dev/console is special are:

- it's an alias for the current console
- it's always opened with O_NOCTTY

Mike.
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