linux-kernel - Re: A question about break and sysrq on a serial console (2.6.19.1)

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Date:	Thu, 18 Jan 2007 09:13:27 +0000
From:	Russell King <rmk+lkml@....linux.org.uk>
To:	Brian Beattie <brianb@...on.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: A question about break and sysrq on a serial console (2.6.19.1)

On Wed, Jan 17, 2007 at 03:56:54PM -0800, Brian Beattie wrote:
> I'm trying to do a SYSRQ over a serial console.  As I understand it a
> break will do that, but I'm not seeing the SYSRQ.  In looking at
> uart_handle_break() in drivers/serial/8250.c it looks like the code will
> toggle port->sysrq, rather than just setting it when the port is a
> console.  I think the correct code would be to move the "port->sysrq =
> 0;" to follow the closing brace on the next line, or am I missing
> something.

Thereby preventing the action of <break> (which may be to cause a SAK
event, which would be rather important on a console to ensure that
you're really logging in rather than typing your password into another
users program which just looks like a login program.)

Note that the sequence for sysrq is:

(non-break characters or nothing) <break> <sysrq-char>

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:
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