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Subject: Re: ARC no console output (was Re: [PATCH 1/2] init/console: Use
 ttynull as a fallback when there is no console)
To:     John Ogness <john.ogness@linutronix.de>,
        Vineet Gupta <vgupta@synopsys.com>,
        Petr Mladek <pmladek@suse.com>,
        Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
        Steven Rostedt <rostedt@goodmis.org>
Cc:     Linus Torvalds <torvalds@linux-foundation.org>,
        Guenter Roeck <linux@roeck-us.net>,
        Shreyas Joshi <shreyas.joshi@biamp.com>,
        shreyasjoshi15@gmail.com,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
        linux-kernel@vger.kernel.org, buildroot@busybox.net,
        Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
        linux-arch@vger.kernel.org,
        arcml <linux-snps-arc@lists.infradead.org>
References: <20201111135450.11214-1-pmladek@suse.com>
 <20201111135450.11214-2-pmladek@suse.com>
 <d2a3b3c0-e548-7dd1-730f-59bc5c04e191@synopsys.com>
 <8735zdm86m.fsf@jogness.linutronix.de>
From:   Greg Ungerer <gerg@linux-m68k.org>
Message-ID: <ac2aaa56-deca-8644-2a42-ca8ee8a77883@linux-m68k.org>
Date:   Thu, 7 Jan 2021 23:14:22 +1000
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Hi John,

On 7/1/21 7:02 pm, John Ogness wrote:
> On 2021-01-06, Vineet Gupta <vgupta@synopsys.com> wrote:
>> This breaks ARC booting (no output on console).
> 
> Could you provide the kernel boot arguments that you use? This series is
> partly about addressing users that have used boot arguments that are
> technically incorrect (even if had worked). Seeing the boot arguments of
> users that are not experiencing problems may help to reveal some of the
> unusual console usages until now.

I can show an example for m68knommu which this change breaks too
(with no console output on boot).

All the ColdFire dev board targets (arch/m68k/configs/m5*) have a 
compiled in boot argument which is "root=/dev/mtdblock0". They have no
real mechanism to pass boot arguments from their boot loader, so it is
compiled in.

The default mcf serial driver is the console on these and no 
"console=ttyS0" argument was required in the past.

Regards
Greg