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Subject: Re: Patch 0727d35de ("Make initramfs honor CONFIG_DEVTMPFS_MOUNT")
 breaks boot
To: Petr Mladek <pmladek@suse.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>,
        Yury Norov <ynorov@caviumnetworks.com>,
        Andrew Morton <akpm@linux-foundation.org>,
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        Prarit Bhargava <prarit@redhat.com>, Yang Shi <yang.shi@linaro.org>,
        Rasmus Villemoes <linux@rasmusvillemoes.dk>,
        Kees Cook <keescook@chromium.org>, Emese Revfy <re.emese@gmail.com>,
        Fabian Frederick <fabf@skynet.be>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
References: <20170522120550.ekrq6ipfmkdtlxjo@yury-N73SV>
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 <1fb53a8c-6c17-1de2-493c-0bff403c9ff9@landley.net>
 <20170911114535.GL8741@pathway.suse.cz>
From: Rob Landley <rob@landley.net>
Message-ID: <a4891f3a-2cab-858c-1a5d-9356fa74ca63@landley.net>
Date: Tue, 12 Sep 2017 21:45:58 -0500
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On 09/11/2017 06:45 AM, Petr Mladek wrote:
>> Except for the second printk line: If you boot with rdinit=/bin/hush
>> then the first time you mount -t devtmpfs /dev /dev after boot (with
>> CONFIG_DEVTMPFS_MOUNT already having mounted it), you get the 0 return
>> value but the last printk() doesn't output? The second and later times
>> you repeat it, both printk() lines are output.
>>
>> What's up with printk?
>>
>> (I added the second printk because the _first_ one wasn't outputting
>> that first time. Something is happening to flush the printk() queue
>> instead of writing it out?
> 
> You need to add "\n" at the end of the line. Otherwise, it expects
> that the message would continue and puts it into a cont buffer.
> The buffer is flushed only when another non-continuous message
> is added.

Ah. The next one flushes the previous one, meaning when I repeat the
command I get the output I expected the second time but I'm seeing the
_previous_ instance of it, not the current one.

> This problem is more visible since the commit 5c2992ee7fd8a29d0412
> ("printk: remove console flushing special cases for partial buffered
> lines").

Gotcha. My bad.

Thanks,

Rob