linux-kernel - Re: [PATCH] x86/earlyprintk: setup earlyprintk as early as possible

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Message-ID: <CAE9FiQWutvBcFJ0MWBBVN3VyXejLZzVdJ5qBCQEox4w_HV7SPw@mail.gmail.com>
Date:	Tue, 7 Apr 2015 12:07:31 -0700
From:	Yinghai Lu <yinghai@...nel.org>
To:	Alexander Kuleshov <kuleshovmail@...il.com>
Cc:	Ingo Molnar <mingo@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86/earlyprintk: setup earlyprintk as early as possible

On Tue, Apr 7, 2015 at 3:31 AM, Alexander Kuleshov
<kuleshovmail@...il.com> wrote:

>
> As i already wrote, i tested it for x86_64 and it works. I will put earlyprintk
> setup in the start of the i386_start_kernel, will test it with 32-bit
> and resend two
> patches if they will be good.

No, that is not enough.
early_printk would handle not only serial console with io port accessing.
You need to make sure all other path including pciserial/dbgp/efi is safe.
They are using early_ioremap, and you can not call early_ioremap()
before early_ioremap.

otherwise you may need to just search "serial string in boot command line" like
i did in moving earlycon early patch.

    Yinghai

View attachment "setup_early_console_x1_pa_symbol_before_earlcon.patch" of type "text/x-patch" (4256 bytes)