linux-kernel - Re: Early printk behaviour

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Message-ID: <8bd0f97a0708160947x3bd308abmc4f3b523e2444586@mail.gmail.com>
Date:	Thu, 16 Aug 2007 12:47:41 -0400
From:	"Mike Frysinger" <vapier.adi@...il.com>
To:	"Gerd Hoffmann" <kraxel@...hat.com>
Cc:	"Robin Getz" <rgetz@...ckfin.uclinux.org>,
	linux-kernel@...r.kernel.org
Subject: Re: Early printk behaviour

On 8/16/07, Gerd Hoffmann <kraxel@...hat.com> wrote:
> Robin Getz wrote:
> > I was putting together an early printk implementation for the Blackfin, and
> > was wondering what the expected behaviour was in this situation.
> >
> > When I set up my bootargs earlyprintk=serial,ttyBF0,57600 and have no console
> > defined (no graphical console, no serial console).
> >
> > based on the patch:
> > http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=69331af79cf29e26d1231152a172a1a10c2df511
> >
> > which no longer calls disable_early_printk, the earlyprintk console never gets
> > turned off (because nothing else ever calls register_console). I get
> > everything out the early console, until the init section is released (where
> > the console structure is sitting), and it starts printing out garbage.
> >
> > Is this expected behaviour?
>
> Hmm, sort of, although I didn't think about the case of no real console
> replacing the early console.  The intention of the patch is to have a
> smooth handover from the boot console to the real console.  And, yes, if
> no real console is ever registered the boot console keeps running ...

i think it also occurs in the case where real console != early console

> So you can either let it running and *not* mark it __init, so it can
> keep on going without breaking.  Or you can explicitly unregister your
> boot console at some point, maybe using a late_initcall.

wouldnt a common kernel late_initcall() be more appropriate ?  if
early console hasnt switched over (for whatever reason), then kill it
...
-mike
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