linux-kernel - Re: console=ttyS1 breaks ttyS1 termios and prevents me from logging in

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Date:	Wed, 08 Apr 2015 19:32:29 -0400
From:	Peter Hurley <peter@...leysoftware.com>
To:	Andy Lutomirski <luto@...capital.net>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-serial@...r.kernel.org, Jiri Slaby <jslaby@...e.cz>,
	Theodore Ts'o <tytso@....edu>
Subject: Re: console=ttyS1 breaks ttyS1 termios and prevents me from logging
 in

On 04/08/2015 05:40 PM, Andy Lutomirski wrote:
> On Wed, Apr 8, 2015 at 2:29 PM, Peter Hurley <peter@...leysoftware.com> wrote:
>> Hi Andy,
>>
>> On 04/08/2015 05:17 PM, Andy Lutomirski wrote:
>>> Something strange seems to have happened to my serial console setup.
>>> I boot with console=ttyS1,115200n8 and I have a getty running on
>>> /dev/ttyS1.
>>>
>>> On older kernels, or if I remove the console= boot parameter, then my
>>> getty works fine.  On 3.19.3 with the console= parameter, something's
>>> wrong with termios and I can't log in.  Running:
>>
>> Thanks for the report.
>> 1. Please attach your dmesg.
>> 2. Is this behavior new to 3.19.3? (iow, what was the last version
>>    that you noticed didn't do this)
> 
> I didn't have the problem before I reinstalled this box, upgraded from
> 3.15 to 3.19.3, and updated by Dell iDRAC7 firmware.  Booting into
> 3.13-something does *not* fix the problem, so I'm not at all convinced
> that the kernel version matters much.  I'll try reverting the iDRAC7
> thing, but I don't see why that would make any difference at all to
> Linux.

I think this is related to DRAC; maybe upgrading the firmware reset
the Serial communication settings in the system bios?

1. What's your getty command line?
2. Contents of /proc/tty/driver/serial when you think getty is running
   and waiting for login (shows line signals).

Something to test is if you set getty to local line, does it work then.
I use agetty so my command line is:
	/sbin/getty --noreset -8L 115200 ttyS0 vt102

Regards,
Peter Hurley


> dmesg attached.  I don't even know what to look for there, though.
> 
>>
>> Regards,
>> Peter Hurley
>>
>>> # stty icanon </dev/ttyS1
>>>
>>> breaks line this (partial strace results included):
>>>
>>> ioctl(0, SNDCTL_TMR_TIMEBASE or SNDRV_TIMER_IOCTL_NEXT_DEVICE or
>>> TCGETS, {B115200 opost -isig -icanon -echo ...}) = 0
>>> ioctl(0, SNDCTL_TMR_TIMEBASE or SNDRV_TIMER_IOCTL_NEXT_DEVICE or
>>> TCGETS, {B115200 opost -isig -icanon -echo ...}) = 0
>>> ioctl(0, SNDCTL_TMR_STOP or SNDRV_TIMER_IOCTL_GINFO or TCSETSW,
>>> {B115200 opost -isig icanon -echo ...}) = 0
>>> ioctl(0, SNDCTL_TMR_TIMEBASE or SNDRV_TIMER_IOCTL_NEXT_DEVICE or
>>> TCGETS, {B115200 opost -isig -icanon -echo ...}) = 0
>>> ioctl(0, SNDCTL_TMR_TIMEBASE or SNDRV_TIMER_IOCTL_NEXT_DEVICE or
>>> TCGETS, {B115200 opost -isig -icanon -echo ...}) = 0
>>> write(2, "stty: ", 6stty: )                   = 6
>>> write(2, "standard input: unable to perfor"..., 58standard input:
>>> unable to perform all requested operations) = 58
>>>
>>> IOW, the setting didn't stick.  On the bad kernel, stty works just
>>> fine on ttyS0.  If I switch to using console=ttyS0,115200, then stty
>>> works on ttyS1 and fails on ttyS0.
>>>
>>> I have no idea what's going on here.  I have two apparently identical
>>> boxes.  One of them has this problem and the other doesn't.
>>
> 
> 
> 

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