Break on serial port

Break on serial port

[cfowler]

I remeber a while back being able to send a break on serial console. 
I've been unable to do this under 2.4.17.  Has this feature been turned
off?  Is there a way to turn it back on?

Thanks,
Chris

Re: Break on serial port

[Russell King]

On Tue, Jun 11, 2002 at 11:41:26AM -0400, cfowler wrote:
> I remeber a while back being able to send a break on serial console. 
> I've been unable to do this under 2.4.17.  Has this feature been turned
> off?  Is there a way to turn it back on?

It works fine here.  Please confirm that:

1. your kernel is built with CONFIG_MAGIC_SYSRQ
2. cat /proc/sys/kernel/sysrq returns '1'
3. the serial console port is being held open by some user program (eg,
   getty or init)

If any of the three above are not true, then break<sysrq-key> doesn't work.

-- 
Russell King (rmk@arm.linux.org.uk)                The developer of ARM Linux
             http://www.arm.linux.org.uk/personal/aboutme.html

Re: Break on serial port

[cfowler]

I can not find that ocnfig option anywher in my 2.4.17 tree.  I also
added CONFIG_MAGIC_SYSRQ=y to the top of .config and then did a  make
dep and make bzImage.  Upon boot I did not see a /proc/sys/kernel/sysrq

I did notice this feature in architectures other than i386.

Chris

On Tue, 2002-06-11 at 12:35, Russell King wrote:
> On Tue, Jun 11, 2002 at 11:41:26AM -0400, cfowler wrote:
> > I remeber a while back being able to send a break on serial console. 
> > I've been unable to do this under 2.4.17.  Has this feature been turned
> > off?  Is there a way to turn it back on?
> 
> It works fine here.  Please confirm that:
> 
> 1. your kernel is built with CONFIG_MAGIC_SYSRQ
> 2. cat /proc/sys/kernel/sysrq returns '1'
> 3. the serial console port is being held open by some user program (eg,
>    getty or init)
> 
> If any of the three above are not true, then break<sysrq-key> doesn't work.
> 
> -- 
> Russell King (rmk@arm.linux.org.uk)                The developer of ARM Linux
>              http://www.arm.linux.org.uk/personal/aboutme.html
> 
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Re: Break on serial port

[Russell King]

On Tue, Jun 11, 2002 at 01:14:36PM -0400, cfowler wrote:
> I can not find that ocnfig option anywher in my 2.4.17 tree.  I also
> added CONFIG_MAGIC_SYSRQ=y to the top of .config and then did a  make
> dep and make bzImage.  Upon boot I did not see a /proc/sys/kernel/sysrq

Oops, sorry, you need to enable CONFIG_DEBUG_KERNEL as well.

-- 
Russell King (rmk@arm.linux.org.uk)                The developer of ARM Linux
             http://www.arm.linux.org.uk/personal/aboutme.html