linux-kernel - Re: [patch v2] Fixes and cleanups for earlyprintk aka boot console.

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Date:	Mon, 23 Apr 2007 23:42:40 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Gerd Hoffmann <kraxel@...e.de>
Cc:	linux-kernel@...r.kernel.org, Paul Mundt <lethal@...ux-sh.org>,
	Ralf Baechle <ralf@...ux-mips.org>, Andi Kleen <ak@...e.de>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Richard Henderson <rth@...ddle.net>,
	Ivan Kokshaysky <ink@...assic.park.msu.ru>,
	Paul Mackerras <paulus@...ba.org>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Jeremy Fitzhardinge <jeremy@...p.org>
Subject: Re: [patch v2] Fixes and cleanups for earlyprintk aka boot console.

On Thu, 15 Mar 2007 16:46:39 +0100 Gerd Hoffmann <kraxel@...e.de> wrote:

> The console subsystem already has an idea of a boot console, using the
> CON_BOOT flag.  The implementation has some flaws though.  The major
> problem is that presence of a boot console makes register_console()
> ignore any other console devices (unless explicitly specified on the
> kernel command line).
> 
> This patch fixes the console selection code to *not* consider a boot
> console a full-featured one, so the first non-boot console registering
> will become the default console instead.  This way the unregister call
> for the boot console in the register_console() function actually
> triggers and the handover from the boot console to the real console
> device works smoothly.  Added a printk for the handover, so you know
> which console device the output goes to when the boot console stops
> printing messages.
> 
> The disable_early_printk() call is obsolete with that patch, explicitly
> disabling the early console isn't needed any more as it works
> automagically with that patch.
> 
> I've walked through the tree, dropped all disable_early_printk()
> instances found below arch/ and tagged the consoles with CON_BOOT if
> needed.  The code is tested on x86, sh (thanks to Paul) and mips
> (thanks to Ralf).
> 
> Changes to last version: Rediffed against -rc3, adapted to mips
> cleanups by Ralf, fixed "udbg-immortal" cmd line arg on powerpc.

I get this, across netconsole:

[17179569.184000] console handover: boot [earlyvga_f._0] -> real [tty0]

wanna take a look at why there's cruft in bootconsole->name please?

in grub.conf I have

        kernel /boot/bzImage-2.6.21-rc7-mm1 ro root=LABEL=/ rhgb vga=0x263 netconsole=4444@....168.2.10/eth0,5145@....168.2.33/00:0D:56:C6:C6:CC profile=1 earlyprintk=vga resume=8:5 time

and I'm using

http://userweb.kernel.org/~akpm/config-sony.txt

Thanks.
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