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Date: Wed, 21 Jun 2017 00:26:32 +0900
From: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
To: Steven Rostedt <rostedt@goodmis.org>
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Cc: ksummit <ksummit-discuss@lists.linuxfoundation.org>
Subject: Re: [Ksummit-discuss] [TECH TOPIC] printk redesign
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On (06/20/17 10:36), Steven Rostedt wrote:
> 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.

agree. that's a bit minor at the moment.

	-ss