Re: [PATCH] [RFC] emit-crash-char: Allow diversion of printk output for crash logging

[David VomLehn <dvomlehn@cisco.com>]

Daniel Walker wrote:
> On Thu, 2008-08-07 at 19:20 -0700, David VomLehn wrote:
>> Allow diversion of characters generated through printk so that they can
>> be logged separately. The printk_time variables is made externally visible
>> so that functions processing the diverted characters can parse off the
>> time added if CONFIG_PRINTK_TIME is enabled.
> 
>> +
>>  static void emit_log_char(char c)
>>  {
>> +	emit_crash_char(c);
>> +
>>  	LOG_BUF(log_end) = c;
> 
> Isn't this duplicating the making of a custom console driver? I'm not a
> console expect, but I think you could have a console driver which
> catches this output and logs it..

Yes, you could, but this seems *so much* more straight-forward. Another option I 
considered was changing things so that the first level interface would simply 
output a character, possibly also passing some sort of context pointer. Then 
whatever was called by that interface could call a console driver, if 
appropriate. Even though I think this is really a cleaner way to do this, it also 
involves many more changes than I think are warranted just to get this little 
piece of functionality.

> Another note, usually when submitting new interfaces like this you
> should also submit the code that uses the interface .. In your case you
> might not be able to do that, but it could never be accepted without at
> least one user.

A highly valid criticism. I actually quoted your message to my management in 
order to underscore how important it is that Cisco becomes a good open source 
citizen. Personally, I view it as an absolute must.

> Daniel