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

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Message-ID: <CALCETrUmNKiJDvz2-Q5QBPuqOVA+z9S7As=Pmw1Ef4ZzTXhhSA@mail.gmail.com>
Date:	Wed, 8 Apr 2015 14:40:52 -0700
From:	Andy Lutomirski <luto@...capital.net>
To:	Peter Hurley <peter@...leysoftware.com>
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 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.

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.
>



-- 
Andy Lutomirski
AMA Capital Management, LLC

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