linux-kernel - Re: [PATCH v8 0/3] x86/earlyprintk: setup serial earlyprintk as early as possible

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Message-ID: <20150527125136.GE19582@pd.tnic>
Date:	Wed, 27 May 2015 14:51:36 +0200
From:	Borislav Petkov <bp@...e.de>
To:	Alexander Kuleshov <kuleshovmail@...il.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.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 v8 0/3] x86/earlyprintk: setup serial earlyprintk as
 early as possible

On Wed, May 27, 2015 at 06:12:59PM +0600, Alexander Kuleshov wrote:
> Is it bad or we no need in it? I want to understand not only how
> kernel works, but also why it written so and I can't understand why we
> have 'earlyprintk' (or another feature) in one place and do not have
> in another.

So how hard was it to say that the first time?

That you want to be able to dump interesting parts of the early boot
process and you would like the early console working as early as
possible?

This is what I wanted to know - what is your use case. Not what is there
and what isn't there in the code. That I can figure out by browsing the
code myself. Most of the time, at least. :-)

Now, have you tested this on real hardware? Because your 0/n message
said "qemu" but I don't think that's sufficient. If we're going to
enable early_printk this early, we'd need it working on real hardware
too.

For that I'd suggest adding a 4th, test patch which issues a couple of
numbered early_printk() lines which we could run on a bunch of machines
to see whether it actually works.

Thanks.

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
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