Re: [Ksummit-discuss] [TECH TOPIC] printk redesign

[Andrew Lunn <andrew@lunn.ch>]

On Sat, Jun 24, 2017 at 08:14:11AM -0300, Mauro Carvalho Chehab wrote:
> Em Mon, 19 Jun 2017 12:26:51 -0400
> Steven Rostedt <rostedt@goodmis.org> escreveu:
> 
> > On Mon, 19 Jun 2017 17:20:55 +0200
> > Andrew Lunn <andrew@lunn.ch> wrote:
> > 
> > 
> > > > 4) All other kernel information that's not critical at all, and perhaps
> > > > doesn't even need to be serialized. At least, not against the above.
> > > > This could be cached, and outputted at a later time than when the
> > > > printk() was called.    
> > > 
> > > Developers machine probably have different requirements to production
> > > machines. When debugging during code development, i want the debug
> > > output to be in the correct order, independent of the level. If you
> > > are going to cause reordering, you might want to add a sequence number
> > > to each output, so it is possible to put it back into the correct
> > > order. And it needs to be clear when output is out of order.  
> 
> Even for developers, ensuring the correct order is a must.
> 
> If someone reports me a bug that the Kernel crashed because of some
> driver, I would ask him to enable debug messages and send the crash
> logs with it enabled. 

We also need a clear indication that ordering is broken and should not
be trusted when we get a crash log from some random user.

   Andrew