[Buildroot] Udev generates too many tty dev nodes

Willy Lambert lambert.willy at gmail.com
Thu Jan 17 13:43:55 UTC 2013


2013/1/17 Thomas Petazzoni <thomas.petazzoni at free-electrons.com>:
> Dear Willy Lambert,
>
> On Thu, 17 Jan 2013 14:05:46 +0100, Willy Lambert wrote:
>
>> I do ^^. The bad argument is that I hate having mess on my device,
>> especially when typing "ls /dev". The good one is that if something
>> behave strangly I like to tackle the root cause. It's not an
>> industrial projet, it's a personnal one on which I can take the time I
>> want to look at everything I like :D. And in this case I do *not* have
>> a need for 64 ttys and I did *not* (at least consciently) ask for
>> having them. So somehting, somewhere is doing thing on my back, and I
>> want to know what.
>>
>> udev is supposed to show only what's available or in use. It's sure
>> that some of those devices are not meeting this criterias.
>
> Those devices *are* available. They have been registered by the kernel,
> so they are available, and it makes perfect sense for udev to create
> device files for them.
>
> If you really don't want to see them in /dev, then create a udev rule
> to not create those device files.

This is the solution I want to avoid. I want to prevent the one that
is asking to create those device (so as you light up, it is the
kernel), not to delete them afterwards.

> See the answer at
> http://unix.stackexchange.com/questions/25021/change-the-number-of-generated-dev-tty-devices
> for a hint (not tested, not sure it is the correct way of writing the
> udev rule, check udev's documentation).
>
> At the kernel level, this number of tty is not configurable. It's
> defined by MAX_NR_CONSOLES, and interestingly, this constant is part of
> the kernel to userspace ABI, so I am not sure it is entirely safe to
> change it to some other random value.
>
> Best regards,
>
> Thomas
> --
> Thomas Petazzoni, Free Electrons
> Kernel, drivers, real-time and embedded Linux
> development, consulting, training and support.
> http://free-electrons.com



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