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* [QUERY] User-Mode Linux and /dev/tty*
@ 2013-07-16 15:54 Ramkumar Ramachandra
  2013-07-16 15:59 ` Richard Weinberger
  0 siblings, 1 reply; 6+ messages in thread
From: Ramkumar Ramachandra @ 2013-07-16 15:54 UTC (permalink / raw)
  To: LKML; +Cc: Jeff Dike, Richard Weinberger, Al Viro

Hi,

So, I was trying to boot User-Mode Linux with a modern rootfs with
systemd on it, and found that it wouldn't present me a prompt.  I dug
further, and found out that getty is not able to open /dev/tty1; I
then tried the console-getty.service (which uses /dev/console), and it
worked.  The reason it doesn't work out of the box is that systemd is
not able to figure out whether or not a virtual console subsystem is
present: /dev/tty0 is present for some reason (although I'm not sure
it's a virtual console), and this confuses systemd.

So, my question is: does um Linux have a virtual console subsystem?
If so, then why doesn't it seem to work?  If not, why does /dev/tty0
exist?

Thanks.

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: [QUERY] User-Mode Linux and /dev/tty*
  2013-07-16 15:54 [QUERY] User-Mode Linux and /dev/tty* Ramkumar Ramachandra
@ 2013-07-16 15:59 ` Richard Weinberger
  2013-07-16 16:03   ` Ramkumar Ramachandra
  0 siblings, 1 reply; 6+ messages in thread
From: Richard Weinberger @ 2013-07-16 15:59 UTC (permalink / raw)
  To: Ramkumar Ramachandra; +Cc: LKML, Jeff Dike, Al Viro

Hi!

Am 16.07.2013 17:54, schrieb Ramkumar Ramachandra:
> Hi,
> 
> So, I was trying to boot User-Mode Linux with a modern rootfs with
> systemd on it, and found that it wouldn't present me a prompt.  I dug
> further, and found out that getty is not able to open /dev/tty1; I
> then tried the console-getty.service (which uses /dev/console), and it
> worked.  The reason it doesn't work out of the box is that systemd is
> not able to figure out whether or not a virtual console subsystem is
> present: /dev/tty0 is present for some reason (although I'm not sure
> it's a virtual console), and this confuses systemd.
> 
> So, my question is: does um Linux have a virtual console subsystem?
> If so, then why doesn't it seem to work?  If not, why does /dev/tty0
> exist?

UML does not have CONFIG_VT.
But recent systemd versions can deal with that.

Thanks,
//richard


^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: [QUERY] User-Mode Linux and /dev/tty*
  2013-07-16 15:59 ` Richard Weinberger
@ 2013-07-16 16:03   ` Ramkumar Ramachandra
  2013-07-16 16:10     ` Richard Weinberger
  0 siblings, 1 reply; 6+ messages in thread
From: Ramkumar Ramachandra @ 2013-07-16 16:03 UTC (permalink / raw)
  To: Richard Weinberger; +Cc: LKML, Jeff Dike, Al Viro

Richard Weinberger wrote:
> UML does not have CONFIG_VT.

Not sure what this means.

> But recent systemd versions can deal with that.

Nope, running systemd HEAD.  I only recently figured out how to detect
that um Linux is running [1].

[1]: https://github.com/systemd/systemd/commit/7080ea16

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: [QUERY] User-Mode Linux and /dev/tty*
  2013-07-16 16:03   ` Ramkumar Ramachandra
@ 2013-07-16 16:10     ` Richard Weinberger
  2013-07-16 16:26       ` Ramkumar Ramachandra
  0 siblings, 1 reply; 6+ messages in thread
From: Richard Weinberger @ 2013-07-16 16:10 UTC (permalink / raw)
  To: Ramkumar Ramachandra; +Cc: LKML, Jeff Dike, Al Viro

Am 16.07.2013 18:03, schrieb Ramkumar Ramachandra:
> Richard Weinberger wrote:
>> UML does not have CONFIG_VT.
> 
> Not sure what this means.

UML does not have virtual consoles.

>> But recent systemd versions can deal with that.
> 
> Nope, running systemd HEAD.  I only recently figured out how to detect
> that um Linux is running [1].
> 
> [1]: https://github.com/systemd/systemd/commit/7080ea16
> 

I'm not running HEAD, but opensuse 12.3 (with systemd) works on UML.

Thanks,
//richard

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: [QUERY] User-Mode Linux and /dev/tty*
  2013-07-16 16:10     ` Richard Weinberger
@ 2013-07-16 16:26       ` Ramkumar Ramachandra
  2013-07-16 16:34         ` Richard Weinberger
  0 siblings, 1 reply; 6+ messages in thread
From: Ramkumar Ramachandra @ 2013-07-16 16:26 UTC (permalink / raw)
  To: Richard Weinberger; +Cc: LKML, Jeff Dike, Al Viro

Richard Weinberger wrote:
> UML does not have virtual consoles.

Then why do I see this on my UML box?

# ls /dev/tty* | wc -l
113

Why is it creating unusable devices?  Is drivers/tty.c responsible for
this?  What is it exactly?

> I'm not running HEAD, but opensuse 12.3 (with systemd) works on UML.

Also, what's with all the

   xterm_open : run_helper failed, errno = 2

messages?  (I installed xterm, but it wasn't very enlightening)
How is drivers/xterm.c supposed to work?  And what is mconsole?

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: [QUERY] User-Mode Linux and /dev/tty*
  2013-07-16 16:26       ` Ramkumar Ramachandra
@ 2013-07-16 16:34         ` Richard Weinberger
  0 siblings, 0 replies; 6+ messages in thread
From: Richard Weinberger @ 2013-07-16 16:34 UTC (permalink / raw)
  To: Ramkumar Ramachandra; +Cc: LKML, Jeff Dike, Al Viro

Am 16.07.2013 18:26, schrieb Ramkumar Ramachandra:
> Richard Weinberger wrote:
>> UML does not have virtual consoles.
> 
> Then why do I see this on my UML box?
> 
> # ls /dev/tty* | wc -l
> 113
> 
> Why is it creating unusable devices?  Is drivers/tty.c responsible for
> this?  What is it exactly?

This is not UML specific.
Are you using devtmpfs?

>> I'm not running HEAD, but opensuse 12.3 (with systemd) works on UML.
> 
> Also, what's with all the
> 
>    xterm_open : run_helper failed, errno = 2

2 is ENOENT.
Do you have uml-utils installed?

> messages?  (I installed xterm, but it wasn't very enlightening)
> How is drivers/xterm.c supposed to work?  And what is mconsole?

the xterm drivers opens a xterm on the host side using port-helper.
Mconsole is the management console.
Please read the documentation.

Thanks,
//richard


^ permalink raw reply	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2013-07-16 16:34 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2013-07-16 15:54 [QUERY] User-Mode Linux and /dev/tty* Ramkumar Ramachandra
2013-07-16 15:59 ` Richard Weinberger
2013-07-16 16:03   ` Ramkumar Ramachandra
2013-07-16 16:10     ` Richard Weinberger
2013-07-16 16:26       ` Ramkumar Ramachandra
2013-07-16 16:34         ` Richard Weinberger

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