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

The attached patch Avoid-duplicated-udev-match-rules.patch was also submitted to Debian upstream, but as Debian is switching to systemd and systemd has come with a feature to consolidate device names in a more generic way, this patch is probably not going further. However, since some Ubuntu Phones have not yet fully switch to systemd, a quick patch for this might be valuable.

This patch tries to reuse device names that is already written in tmp rules and has exactly the same match expr with the one that is going to be written out.

Thanks for reporting this patch and help to make ubuntu better.

It's mostly the same people working on implementing systemd in debian and ubuntu (and we push most of our patches to debian experimental for non RC bugs, and then sync in ubuntu), so let's continue the discussion on the debian bug report, shall we?

I let this one opened to ensure Martin has a look as he's way more udev savy than I am :)

Sorry, I don't know that. Just want to have a backup here so that we may still have a chance to pick it up once it's ditched by Debian.

Sure, let's wait for Michael and Martin to comment on this, they are more up to date on the network side of systemd than I am (Martin will be back at the end of week FYI). Thanks for your patch!

The attachment "Avoid duplicated udev match rules" seems to be a patch. If it isn't, please remove the "patch" flag from the attachment, remove the "patch" tag, and if you are a member of the ~ubuntu-reviewers, unsubscribe the team.

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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.

 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.

 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.

(replied inline)

2015-03-26 20:46 GMT+08:00 Martin Pitt <email address hidden>:

> 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

> > create/ship an empty /etc/udev/rules.d/75-persistent-net-generator.rules
> This is doable to me.

OK, that might be the quickest/safest way for now?

> net.ifnames depends on systemd

No, that's udev only. It should work just fine under upstart too. As that's the long-term goal, doing that on touch for vivid+1 could be the the best option, but it's certainly too intrusive for RTM/vivid for now, I figure?

2015-03-26 21:34 GMT+08:00 Martin Pitt <email address hidden>:

> > > create/ship an empty
> /etc/udev/rules.d/75-persistent-net-generator.rules
> > This is doable to me.
>
> OK, that might be the quickest/safest way for now?
>

That follows someone has to cherry-pick the same karg change to each device
affected, which means all because rootfs is always mounted read-only except
for those in very early development stage. So quickest? I'm not so sure. As
for safest, I don't think leaving a obvious defect open counts. It's just
one of the many possible solutions.

We may also choose to ignore this bug and wait until all the devices switch
to systemd and Debian drops
"Make-net.ifnames-opt-in-instead-of-opt-out.patch". So far there is no
fatal symptom reported yet, but a changing device name can certainly affect
automation tools.

For the record, we are going to switch to net.ifnames soon in wily and Debian. See bug 1454254 and https://lists.ubuntu.com/archives/ubuntu-devel/2015-May/038761.html