desktop-packages team mailing list archive

[Vicamo Yang <1435687@xxxxxxxxxxxxxxxxxx>]

(replied inline)

2015-03-26 20:46 GMT+08:00 Martin Pitt <martin.pitt@xxxxxxxxxx>:

> I think this overcomplicates things a lot. I see three options here:
>
>  1) My impression is that we don't actually care about persistant
> interface names on the phone. Therefore, phone image builds could just
> create/ship an empty /etc/udev/rules.d/75-persistent-net-generator.rules
> which will disable the one in /lib/udev/rules.d/ and therefore disable
> the generator completely.
>

This is doable to me.

 2) If we actually do want persistant names across reboots, then
> /etc/udev/rules.d/ needs to become writable. It does not make sense to
> support a phone specific path for this if we could just make the above
> writable.
>

It's not about persistent names across reboots, the interface name will not
be consistent if driver reload happens, and that's what's happening on
embedded devices. Whenever driver reload happens, there will be an ADD
uevent which triggers 75-persistent-net-generator.rules.


>  3) As you already said, we could also enable net.ifnames=1 on the
> kernel command line to use "proper" interface names, which will also
> disable 75-persistent-net-generator.rules.
>

net.ifnames depends on systemd, and Ubuntu Phone is not yet upgrade to use
systemd by default.


> ** Package changed: systemd (Ubuntu) => ubuntu-settings (Ubuntu)


Vicamo

-- 
You received this bug notification because you are a member of Desktop
Packages, which is subscribed to ubuntu-settings in Ubuntu.
https://bugs.launchpad.net/bugs/1435687

Title:
  disable/enable WiFi on devices with read-only rootfs, the wifi network
  name will auto plus 1

Status in systemd:
  Fix Released
Status in ubuntu-settings package in Ubuntu:
  New

Bug description:
  On devices with read-only rootfs, e.g. mobile phones, nic device
  number (wlan<N>) may increase every time disabled and re-enabled. To
  be more precisely, this happens only on devices when disabling a NIC
  removes the corresponding driver.

  "/lib/udev/rules.d/75-persistent-net-generator.rules" checks whether
  NAME attribute has been assigned to wlan<N> device: if yes, skip all
  the followed steps, or, call to "/lib/udev/write_net_rules" to
  generate a persistent device name rule file. That persistent file
  should be created under "/etc/udev/rules.d" and named "70-persistent-
  net.rules", so it guarantees NAME attribute should be assigned if
  available before being read. However, when rootfs was previously
  mounted as read-only, a file "/run/udev/tmp-rules--70-persistent-
  net.rules" is created instead. This temporary file is supposed to be
  moved back into "/etc/udev/rules.d" by a systemd service udev-finish
  right after the system finishes start-up chaos. Again, if rootfs is
  still mounted as read-only, this move will certainly fail. One last
  important thing, /run/udev is _NOT_ included in udev rules inclusion
  paths, so any rules written here will not be taken into account when
  processing uevents.

  So, when wlan0 is probed for the first time on a device with read-only
  rootfs, udev creates "/run/udev/tmp-ruiles--70-persistent-net.rules"
  and inserts one rule for it. When wlan0 is disabled and re-enabled,
  since "/run/udev/tmp-rules--70-persistent-net.rules" is not taken into
  account, its NAME attribute will not be set, and udev recognize it as
  a new nic and tries to write another rule for it again. However, in
  this time, "wlan0" has been taken in the previously written temporary
  rules file, so "wlan1" is chosen instead, and an exactly the same
  matching rule (except for NAME= part) is appended to "/run/udev/tmp-
  rules--70-persistent-net.rules". When the device is again disabled and
  re-enabled, "wlan2" will be assigned. And so on ....

  This is a cloned bug from Debian bug 780705 (https://bugs.debian.org
  /cgi-bin/bugreport.cgi?bug=780705), which affects Ubuntu Phone.

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