Re: Anyone using SysRQ key sequences on console serial port ?

I am enable to get one keyboard sequence responded to with the noted change
in the dts .

 for instance:

   SysRQ ( Break)   c

  Panics .. Which is a good response, and since it doesn't require a return
to user mode ( I suspect )  it appears to work.

Any other requests fail to report any information :

 SysRQ (break )  l - list active processes
                         m - list memory

  Any additional SysRQ are ignored., and the system appears hung.

 On an reference Intel platform, multiple SyqRQ can be issued and the
system remains healthy .









On Mon, Feb 17, 2014 at 1:37 PM, Scott Wood [off-list ref] wrote:

On Sun, 2014-02-16 at 10:56 -0500, Paul Gortmaker wrote:

quoted

On Fri, Feb 14, 2014 at 3:42 PM, John Donnelly [off-list ref]

wrote:

quoted

quoted

Hi,

 I tried using the SysRq hotkey sequence on a serial console -
3.11.0-5-powerpc-e500mc system, by issuing a " break " and the system
immediately wedges after displaying "SysRQ : HELP : " using both

"Putty" and

quoted

quoted

"Teraterm"  terminal emulators. I know the system is dead because my

ssh

quoted

quoted

sessions stopped too.

Yes it does work -- or at least it _did_ work.  Make sure your dts has

an entry

quoted

                        compatible = "fsl,ns16550", "ns16550";

since that enables a workaround I'd added for a hardware errata relating
to sending breaks over the serial console.   What you describe above
makes me think you aren't getting the workaround enabled.

Also make sure CONFIG_SERIAL_8250_FSL is enabled.

-Scott

-- 

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* John.*

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