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

[Steven Rostedt <rostedt@goodmis.org>]

On Tue, 20 Jun 2017 10:24:43 +0200
Arnd Bergmann <arnd@arndb.de> wrote:


> > It'd be nice if, when building a kernel with CONFIG_PRINTK disabled, the
> > full format-string handling wasn't compiled in to handle snprintf and
> > family. In particular, some of the kernel-specific %p format-string
> > modifiers only get used when printing to a user, never when formatting a
> > string for machine consumption. I can think of a few different ways to
> > address that, but I'd love to see that taken into account in the
> > requirements for a printk redesign.  
> 
> I don't think that's realistic, given how many special formats we have
> nowadays, see the discussion about the 'struct rtc_time' format recently,
> which was definitely meant for external ABIs.

I think it may be possible, but it is a separate project from the
printk one. One thing, tracing requires it, and does not require
printk. What you could do is have CONFIG_VSPRINTF and have anything that
uses it select it as well. Which would be printk, tracing, etc.

But the printk mess in general is a big enough issue to try to solve
than to bring this up at this time.

-- Steve