linux-kernel - Re: [PATCH v11 3/5] x86/earlyprintk: Allocate early log

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Message-ID: <CANCZXo4zoxc9273wJk+V+9JfxnJNnNCuwguhzxTJZSd9i=FTaQ@mail.gmail.com>
Date:	Tue, 9 Jun 2015 23:37:27 +0600
From:	Alexander Kuleshov <kuleshovmail@...il.com>
To:	Borislav Petkov <bp@...e.de>
Cc:	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Mark Rustad <mark.d.rustad@...el.com>,
	Yinghai Lu <yinghai@...nel.org>
Subject: Re: [PATCH v11 3/5] x86/earlyprintk: Allocate early log_buf as early
 as possible

On Tue, Jun 09, 2015 at 06:58:52PM +0300, Andy Shevchenko wrote:
>> On Tue, 2015-06-09 at 17:11 +0600, Alexander Kuleshov wrote:
>> > This patch moves call of the early setup_log_buf from the
>> > arch/x86/kernel/setup.c to the arch/x86/kernel/head{32,64}.c
>> > and updates log_buf with the earlyprintk messages.
>> >
>>
>> Didn't mention lockdep_init() change. Regarding to what Borislav told
>> you how do you handle double call of lockdep_init()?
>>

Double call of the lockdep_init is safe, since it has

if (lockdep_initialized)
                return;

at the beginning. Will update commit message with it.

>> Also, when you print the same message to the serial and to kernel
>> buffer, do you avoid duplication? Your early_printk messages needs flag
>> LOG_NOCONS if I understand correctly.

Yes, just checked. They will be duplicated. Thanks for advice about LOG_NOCONS.

Borislav, I'm really not sure too, that using of printk to update
log_buf with the earlyprintk
is a right correct here. So, we can update log_buf with earlyprintk
messages with the call
of the

log_store(0, LOGLEVEL_DEFAULT, LOG_NOCONS|LOG_CONT, 0, NULL, 0,
              buf, strlen(buf));

in the early_printk function. What do you think about it?

Do we need to see earlyprintk messages in the dmesg output? Maybe
there need to create yet another option, something like:

CONFIG_EARLY_PRINTK_KERNEL_LOG

or something like this?
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