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Date: Sat, 22 Feb 2014 08:40:24 -0500
From: Peter Hurley <peter@hurleysoftware.com>
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To: David Herrmann <dh.herrmann@gmail.com>,
	Hannes Reinecke <hare@suse.de>
CC: Ray Strode <halfline@gmail.com>, Kay Sievers <kay@vrfy.org>,
	Josh Boyer <jwboyer@fedoraproject.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"Linux-Kernel@Vger. Kernel. Org" <linux-kernel@vger.kernel.org>,
	"stable@vger.kernel.org" <stable@vger.kernel.org>,
	Lennart Poettering <lennart@poettering.net>,
	Jiri Slaby <jslaby@suse.cz>, Werner Fink <werner@suse.de>
Subject: Re: [PATCH 3.13 35/99] tty: Set correct tty name in active sysfs
 attribute
References: <20140220235118.191692546@linuxfoundation.org>	<20140220235119.236520201@linuxfoundation.org>	<CA+5PVA55O2GwUE8oMHShgKgQPA89z5RTbn6yCvOPBMGsf70kBw@mail.gmail.com>	<5307683C.50209@suse.de>	<CA+5PVA5W=t9+OmZXZuJT-1EsZXmTUBrX4eHjJcmQg676SOjSng@mail.gmail.com>	<CAPXgP12Vs3LtVPOxF-Tnn4H7NjD6unXtPEOjFzRRhJhf0xndRQ@mail.gmail.com>	<CAA_UwzK38FpDgv0RKfQG_QZd-OttZBQC60UffbyUGWq8E05PpQ@mail.gmail.com> <CANq1E4T25a3JkYB_JggtueygqpGVn0vBmaMZXvohWb_jinxuag@mail.gmail.com>
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On 02/22/2014 08:25 AM, David Herrmann wrote:
> Hi
>
> On Fri, Feb 21, 2014 at 11:53 PM, Ray Strode <halfline@gmail.com> wrote:
>> Hi,
>>
>> On Fri, Feb 21, 2014 at 11:01 AM, Kay Sievers <kay@vrfy.org> wrote:
>>> Why did the tty0 change to tty1 now? That doesn't look like a "driver
>>> name" vs. "device name" issue?
>>
>> I don't know if it's intentional, but the patch does:
>> +               int index = cs[i]->index;
>> ...
>> +               driver = cs[i]->device(cs[i], &index);
>>
>> which will presumably change the index from 0 to 1 because of this code:
>>
>> static struct tty_driver *vt_console_device(struct console *c, int *index)
>> {
>>         *index = c->index ? c->index-1 : fg_console;
>>         return console_driver;
>> }
>>
>> At least that's what it looks like is causing the problem from
>> browsing through the source a bit.
>
> Yepp, that's it. So if you configure the console to always be
> redirected to the foreground terminal, you simply bind it to tty0 and
> this file used to return tty0 then.
> With this patch, we actually return the foreground terminal instead,
> so tty0 is resolved to the real VT. This sounds like the correct
> behavior (even though it currently breaks poll() on this file). But if
> it breaks stuff, we should revert it and add a second file just like
> Peter suggested.

Or add sysfs entries for each console that exposes the device, so
that the underlying device is trivially discoverable, which is the
original problem.

Regards,
Peter Hurley