Re: [patch 1/3] kmsg: Kernel message catalog macros.

[Martin Schwidefsky <schwidefsky@de.ibm.com>]

On Tue, 2008-08-12 at 17:35 -0700, Tim Hockin wrote:
> On Wed, Jul 30, 2008 at 9:56 AM, Martin Schwidefsky
> <schwidefsky@de.ibm.com> wrote:
> > From: Michael Holzheu <holzheu@de.ibm.com>
> > From: Martin Schwidefsky <schwidefsky@de.ibm.com>
> >
> > Introduce a new family of printk macros which prefixes each kmsg message
> > with a component name and allows to tag the printk with a message id.
> 
> We've been talking about doing something like this, just this week.  AKPM
> pointed me at this thread.  Good timing. :)

Good to hear that we are not the only one working on this.

> > +#define kmsg_dev_alert(id, dev, format, arg...) \
> > +    printk(__KMSG_CHECK(ALERT, id) KMSG_COMPONENT \
> > +        ": %s: " format, (dev)->bus_id , ## arg)
> 
> Rather than the gcc-specific '## arg', shouldn't we use the standard C99
> form: '##__VA_ARGS__'  ?

Ok, I changed the macros accordingly.

> As a format, I would argue to leave out the spaces after colons, making
> the inevitable string splitting even easier.

Makes sense and it does not make the message harder to read.

> I don't care for the magic file-global KMSG_COMPONENT.  It just feels
> wrong.  In most cases, I want the prefix to be hierarchical.  For example,
> rather than "tg3" I want "net.tg3" or "netdev:tg3" or something.

But what is the alternative to the #define to specify the base name of
the message tag? KBUILD_MODNAME has been proposed but I don't think this
is a good idea since I want the message tags to be independent of the
code structure.

> Further, We want to make a clearer denotation between "just another
> printk()" and these things, which are really "important events".  Maybe a
> global prefix that makes it easy to seperate them out?  Or a parallel
> "event" interface that logs to printk() and a netlink socket?

Well the kmsg macros distinguish between id==0 and id>0 messages. For a
id==0 message there is no documentation required and the kmsg prefix
will be just the KMSG_COMPONENT. You could consider that to be "just
another printk". For id>0 the kmsg macros will create the tuppel
KMSG_COMPONENT.ID so you already can separate "normal" and "important"
prinkts.

-- 
blue skies,
  Martin.

"Reality continues to ruin my life." - Calvin.