[Buildroot] [PATCH 06/20] system: move setting getty to the corresponding init systems

[Arnout Vandecappelle <arnout@mind.be>]

On 22-07-17 21:57, Thomas Petazzoni wrote:
> Hello,
> 
> On Sat, 22 Jul 2017 15:11:57 +0200, Arnout Vandecappelle wrote:
[snip]
>>  The only difference between these two is that for sysvinit we have to make sure
>> it's only 4 characters. But it actually doesn't hurt to do the same for busybox
>> as well. So perhaps we can factor the two in a single SYSTEM_SET_GETTY ?
> 
> I am not sure if that works, because the semantic of the first field is
> not the same between sysvinit and Busybox init.

 Right! I thought busybox init just ignored it, I forgot about the controlling
terminal.

 Regards,
 Arnout

> 
> For sysvinit (http://www.manpages.info/linux/inittab.5.html)
> 
>        id     is a unique sequence of 1-4 characters which identifies an entry
> 	      in inittab (for versions of sysvinit compiled with  libraries  <
> 	      5.2.18 or a.out libraries the limit is 2 characters).
> 
> 	      Note:  For  gettys or other login processes, the id field should
> 	      be the tty suffix of the corresponding tty,  e.g.	 1  for	 tty1.
> 	      Otherwise, the login accounting might not work correctly.
> 
> For Busybox init:
> 
> # <id>: WARNING: This field has a non-traditional meaning for BusyBox init!
> #
> #       The id field is used by BusyBox init to specify the controlling tty for
> #       the specified process to run on.  The contents of this field are
> #       appended to "/dev/" and used as-is.  There is no need for this field to
> #       be unique, although if it isn't you may have strange results.  If this
> #       field is left blank, then the init's stdin/out will be used.
> 
> Hence, with Busybox init, if you pass a truncated "id", the command
> might fail to run as it will try to open a /dev/<something> that
> doesn't exist. So, if you truncate ttyAMA0, it will be just ttyA,
> Busybox will try to open /dev/ttyA and it will fail.
> 
> Best regards,
> 
> Thomas
> 

-- 
Arnout Vandecappelle                          arnout at mind be
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