[systemd-devel] systemd, getty and udev

[Andrey Borzenkov]

On Wed, Mar 23, 2011 at 2:38 PM, Kay Sievers <kay.sievers at vrfy.org> wrote:
> On Wed, Mar 23, 2011 at 12:33, Michael Olbrich <m.olbrich at pengutronix.de> wrote:
>> On Wed, Mar 23, 2011 at 02:00:56PM +0300, Andrey Borzenkov wrote:
>>> On Wed, Mar 23, 2011 at 10:22 AM, Michael Olbrich
>>> <m.olbrich at pengutronix.de> wrote:
>>> > On Mon, Mar 21, 2011 at 08:05:44PM +0300, Andrey Borzenkov wrote:
>>> >> On Mon, Mar 21, 2011 at 6:06 PM, Michael Olbrich
>>> >> <m.olbrich at pengutronix.de> wrote:
>>> >>
>>> >> >> The default systemd files only start getties on a handful of ttys. Since
>>> >> >> it seems impossible to distinguish between display ttys and e.g. modem
>>> >> >> ttys, one can't just simply start gettys on all tty*, thus necessiting
>>> >> >> manual addition for further ttys in the udev rules.
>>> >> >
>>> >> > hmmm, that is unfortunate. There are a lot of different names for the
>>> >> > serial ports on embedded systems. And using a serial console here is rather
>>> >> > common. Maybe the tty from /sys/class/tty/console/active can always be
>>> >> > added somehow?
>>> >> >
>>> >>
>>> >> src/getty-generator.c:        if
>>> >> (read_one_line_file("/sys/class/tty/console/active", &active) >= 0) {
>>> >
>>> > That's not what I meant. This only adds the serial tty unit. However it is
>>> > never started unless the associated device gets the udev 'systemd' tag.
>>> >
>>>
>>> This unit is also added as WantedBy to getty.target; and getty.target
>>> should be pulled in by multi-user.target. Does not it happen?
>>>
>>> Or do you mean, it should be always unconditionally started?
>>
>> The units are all added correctly but without the "systemd" tag in udev
>> "systemd[1]: dev-ttyAMA0.device changed dead -> plugged" never happens.
>> As a result the getty is never started.
>
> I guess, we could just add all 'special' ttys like:
>  KERNEL=="tty[a-zA-Z]*"
>

May be this special console unit simply need not be bound to device?
Is it even possible for console to disappear?