Re: Sun IPX and PPS via serial port

[Erik Fair <fair%netbsd.org@localhost>]

On Aug 20, 2011, at 13:13 , David Laight wrote:

>> kernel console output is not handled like userland output.  it is
>> done with a polling method, and that is what locks out some of the
>> other interrupts during this time.
> 
> Sometimes you want that behaviour.
> On some systems syslogd does the console output, so you have to kill
> it to get direct output.

There needs to be a distinction in console output between panics and other 
immediately urgent messages about state corruption that must get out before the 
next state change (and maybe a crash or hang), and those messages which are 
merely "nice to know". The former should continue to disable interrupts (and 
other processing) until the message is completely printed, but they should be 
rare and sparingly used (as a comment in the ancient UNIX sources for the 
kernel printf once said, "this routine should not be used for idle chit-chat"). 
The latter should be done in such a way that the rest of the system operates as 
normal with as little disruption as possible (i.e. interrupts enabled).

        Erik <fair%netbsd.org@localhost>