dummy ethernet devices and sysfs

dummy ethernet devices and sysfs

[Warren Turkal]

Hi,

I was looking through sysfs today, and something interesting jumped
out at me after I loaded the dummy module.

This directory exists: /sys/class/net/wlp2s0/device/

This directory does not: /sys/class/net/dummy0/device/

I can find the module that is providing the wlp2s0 device with the following:
$ ls /sys/class/net/wlp2s0/device/driver/module/drivers/
pci:iwlwifi

Shouldn't dummy have something similar so that one can figure out
which module is providing the dummy0 device?

FWIW, I am running the latest Ubuntu 15.10 kernel (4.2.0-23-generic).

Thanks,
wt

Re: dummy ethernet devices and sysfs

[Stephen Hemminger]

On Wed, 13 Jan 2016 11:58:01 -0800
Warren Turkal <wt@penguintechs.org> wrote:

> Hi,
> 
> I was looking through sysfs today, and something interesting jumped
> out at me after I loaded the dummy module.
> 
> This directory exists: /sys/class/net/wlp2s0/device/
> 
> This directory does not: /sys/class/net/dummy0/device/
> 
> I can find the module that is providing the wlp2s0 device with the following:
> $ ls /sys/class/net/wlp2s0/device/driver/module/drivers/
> pci:iwlwifi
> 
> Shouldn't dummy have something similar so that one can figure out
> which module is providing the dummy0 device?
> 
> FWIW, I am running the latest Ubuntu 15.10 kernel (4.2.0-23-generic).
> 
> Thanks,
> wt

If you look carefully at the /sys/class/net/wlp2s0/device/ you will
see it is a symlink to the underlying /sys directory for the hardware (PCI)
device.  Since dummy (and other virtual interfaces) have no hardware,
there is no symlink.

Re: dummy ethernet devices and sysfs

[Warren Turkal]

On Wed, Jan 13, 2016 at 12:16 PM, Stephen Hemminger
<stephen@networkplumber.org> wrote:
> If you look carefully at the /sys/class/net/wlp2s0/device/ you will
> see it is a symlink to the underlying /sys directory for the hardware (PCI)
> device.  Since dummy (and other virtual interfaces) have no hardware,
> there is no symlink.

What's the right way for one find the module that caused dummy0 to exist?

wt

On Wed, Jan 13, 2016 at 12:16 PM, Stephen Hemminger
<stephen@networkplumber.org> wrote:
> On Wed, 13 Jan 2016 11:58:01 -0800
> Warren Turkal <wt@penguintechs.org> wrote:
>
>> Hi,
>>
>> I was looking through sysfs today, and something interesting jumped
>> out at me after I loaded the dummy module.
>>
>> This directory exists: /sys/class/net/wlp2s0/device/
>>
>> This directory does not: /sys/class/net/dummy0/device/
>>
>> I can find the module that is providing the wlp2s0 device with the following:
>> $ ls /sys/class/net/wlp2s0/device/driver/module/drivers/
>> pci:iwlwifi
>>
>> Shouldn't dummy have something similar so that one can figure out
>> which module is providing the dummy0 device?
>>
>> FWIW, I am running the latest Ubuntu 15.10 kernel (4.2.0-23-generic).
>>
>> Thanks,
>> wt
>
> If you look carefully at the /sys/class/net/wlp2s0/device/ you will
> see it is a symlink to the underlying /sys directory for the hardware (PCI)
> device.  Since dummy (and other virtual interfaces) have no hardware,
> there is no symlink.