[Buildroot] Howto change group of /dev/snd when using devtmpfs

[Buildroot] Howto change group of /dev/snd when using devtmpfs

[Jörg Krause]

Hi,

I need some help to get the group changed for "/dev/snd" when using
devtmpfs. By default, "/dev/snd" and subnodes have the following
settings:

"""
# ls -l /dev/snd/
total 0
crw-------????1 root?????root??????116,???0 Jan??1??1970 controlC0
crw-------????1 root?????root??????116,??16 Jan??1??1970 pcmC0D0p
crw-------????1 root?????root??????116,??25 Jan??1??1970 pcmC0D1c
crw-------????1 root?????root??????116,??33 Jan??1??1970 timer
"""

I'd like to change the group to audio.

Best regards,
J?rg Krause

[Buildroot] Howto change group of /dev/snd when using devtmpfs

[Arnout Vandecappelle]

On 23-03-17 18:22, J?rg Krause wrote:
> Hi,
> 
> I need some help to get the group changed for "/dev/snd" when using
> devtmpfs. By default, "/dev/snd" and subnodes have the following
> settings:
> 
> """
> # ls -l /dev/snd/
> total 0
> crw-------    1 root     root      116,   0 Jan  1  1970 controlC0
> crw-------    1 root     root      116,  16 Jan  1  1970 pcmC0D0p
> crw-------    1 root     root      116,  25 Jan  1  1970 pcmC0D1c
> crw-------    1 root     root      116,  33 Jan  1  1970 timer
> """
> 
> I'd like to change the group to audio.

 That's exactly what mdev and (e)udev are meant for. devtmpfs creates device
nodes automatically but only with defaults (default names, default user/group,
default permissions). If you want to change anything, you need a helper.

 Of course, you can also write a script as /sbin/hotplug. But then I wonder why
not use mdev - it hardly increases the busybox size.

 Regards,
 Arnout

-- 
Arnout Vandecappelle                          arnout at mind be
Senior Embedded Software Architect            +32-16-286500
Essensium/Mind                                http://www.mind.be
G.Geenslaan 9, 3001 Leuven, Belgium           BE 872 984 063 RPR Leuven
LinkedIn profile: http://www.linkedin.com/in/arnoutvandecappelle
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[Buildroot] Howto change group of /dev/snd when using devtmpfs

[Jörg Krause]

Hi Arnout,

On Thu, 2017-03-23 at 21:38 +0100, Arnout Vandecappelle wrote:
> 
> On 23-03-17 18:22, J?rg Krause wrote:
> > Hi,
> > 
> > I need some help to get the group changed for "/dev/snd" when using
> > devtmpfs. By default, "/dev/snd" and subnodes have the following
> > settings:
> > 
> > """
> > # ls -l /dev/snd/
> > total 0
> > crw-------????1 root?????root??????116,???0 Jan??1??1970 controlC0
> > crw-------????1 root?????root??????116,??16 Jan??1??1970 pcmC0D0p
> > crw-------????1 root?????root??????116,??25 Jan??1??1970 pcmC0D1c
> > crw-------????1 root?????root??????116,??33 Jan??1??1970 timer
> > """
> > 
> > I'd like to change the group to audio.
> 
> ?That's exactly what mdev and (e)udev are meant for. devtmpfs creates
> device
> nodes automatically but only with defaults (default names, default
> user/group,
> default permissions). If you want to change anything, you need a
> helper.
> 
> ?Of course, you can also write a script as /sbin/hotplug. But then I
> wonder why
> not use mdev - it hardly increases the busybox size.

Thanks! I tried mdev before, but it didn't work. After some digging I
found that the mdev.conf in Buildroot is outdated, because the syntax
changed?[1] in Busybox 1.23.

Strange, that nobody noticed this for two years...

[1] http://lists.busybox.net/pipermail/busybox/2015-February/082297.htm
l

J?rg