[Buildroot] editing device_table_dev.txt

Arnout Vandecappelle arnout at mind.be
Thu Feb 21 23:24:11 UTC 2013

On 22/02/13 00:07, Stefan Fröberg wrote:
> 22.2.2013 0:57, Arnout Vandecappelle kirjoitti:
>> On 21/02/13 11:32, Stefan Fröberg wrote:
>>>>>>>>> Also kernel .config file should also have CONFIG_DEVTMPFS and
>>>>>>>>> as 'y'.
>>>>>>> Sorry, that should have been CONFIG_DEVTMPFS=y and
>>>>> Kernel version 2.6.30 is too old for that.
>>>>> baruch
>>> It is ?
>>> Damn, then the only options are mdev and udev.
>>   I'm afraid that mdev and udev no longer work with old kernels that
>> don't support the DEVTMPFS option...
>>   mdev and udev don't create device nodes; they only do something
>> configurable when a hotplug event happens.
> What you mean that mdev or udev does not create device nodes ???
> If older kernels don't support devtmpfs like Baruch
> said then who does that device node creation if not the mdev or udev
> when event happens ???

  Well, nobody...

  Turns out that mdev still does device node creation. Makes me wonder if 
I'm not mistaken about udev as well... I just remember hearing that 
device node creation was removed when DEVTMPFS was introduced.

>>   That said, you can create custom mdev/udev rules to create device
>> nodes. But it's all manual - and much simpler to just create the
>> device nodes manually.
> for mdev it's just a single file, /etc/mdev.conf (I can even copy-paste
> it here, it's not that long and will cover 99% of needs).

  Yes, but that file just specifies the chmod/chown rules, not how to 
create the device nodes. But as I just saw in the code, mdev does in fact 
create the device nodes.


> for udev it punch of rules found under /lib/udev/rules.d and yes, it can
> get really tedious to play games with those files if some device node is
> not created or
> is not created with right permissions or whatever.


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
GPG fingerprint:  7CB5 E4CC 6C2E EFD4 6E3D A754 F963 ECAB 2450 2F1F

More information about the buildroot mailing list