networking fails in 32-bit 14.04 using HyperV on Win2012R2

[Chris Norris]

I was running Ubuntu 13.10 32-bit as a VM on a Windows Server 2012 R2 machine with Hyper-V. In 32-bit 13.10, networking worked properly at all times, from the first installation to normal usage.

I ran the upgrade to 32-bit Ubuntu 14.04 and discovered that networking is no longer working.

To eliminate the possibility that there was a botched upgrade, I tried a fresh install in another VM.

I performed a fresh install of 32-bit Ubuntu 14.04 in Hyper-V from ubuntu-14.04-desktop-i386.iso, and I noticed that the network was not connecting during the first part of the installation before any files are copied to the disk. After the installation completed, there was no eth0 device present.

By comparison, I performed a fresh install of 64-bit Ubuntu 14.04 in Hyper-V from the ubuntu-14.04-desktop-amd64.iso, and networking worked properly at all times from the start of installation.

To summarize, networking is failing in 32-bit Ubuntu 14.04 under Hyper-V in Windows Server 2012 R2. Networking is working properly in 32-bit Ubuntu 13.10 on the same machine. Networking is working properly in 64-bit Ubuntu 14.04 on the same machine.

Any suggestions on getting 32-bit Ubuntu 14.04 to work in my Hyper-V VM ?

Thanks.

[Ubuntu Foundations Team Bug Bot (crichton)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. It seems that your bug report is not filed about a specific source package though, rather it is just filed against Ubuntu in general. It is important that bug reports be filed about source packages so that people interested in the package can find the bugs about it. You can find some hints about determining what package your bug might be about at https://wiki.ubuntu.com/Bugs/FindRightPackage. You might also ask for help in the #ubuntu-bugs irc channel on Freenode.

To change the source package that this bug is filed about visit https://bugs.launchpad.net/ubuntu/+bug/1338185/+editstatus and add the package name in the text box next to the word Package.

[This is an automated message. I apologize if it reached you inappropriately; please just reply to this message indicating so.]

[Brad Figg (brad-figg)]

This bug is missing log files that will aid in diagnosing the problem. From a terminal window please run:

apport-collect 1338185

and then change the status of the bug to 'Confirmed'.

If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'.

This change has been made by an automated script, maintained by the Ubuntu Kernel Team.

[Chris Norris (clnorris)]

I was requested to run the command "apport-collect 1338185".

The reason for the bug is that all my 32-bit Ubuntu 14.10 installations in Hyper-V do not have a network device. Therefore, I followed the next instructions:

"If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'."

I manually changed the bug status to Confirmed.

[Joseph Salisbury (jsalisbury)]

Can you see if this bug also affects the latest 32 bit daily image, which is available from:
http://cdimage.ubuntu.com/daily-live/current/

[MG (heyrastamon)]

I encountered the exact same issue with loss of network upgrading Ubuntu 12.04LTS 32-bit to 14.04LTS 32-bit on a Hyper-V VM (Windows 2008R2). I went through the same steps to do a fresh install of 14.04LTS 32-bit and had the same result. Also found Ubuntu 14.04LTS 64-bit worked well and did not experience this issue.

After much testing, I found that if I dropped the RAM of the Ubuntu 14.04LTS VM to 4014MB on 2008R2 Hyper-V (4026MB on Hyper-V 2012R2), the network adapter will show up and network connectivity will resume (Will have internal system errors however). I then dropped to 2048MB and Ubuntu is stable and network is connected. My Ubuntu 12.04LTS 32-bit VMs run 4GB wonderfully and never experienced issues with memory/networking.

Also tested on different hosts and found this network issue is the same on Hyper-V versions 2008R2, 2012 and 2012R2 when memory is pushed to 4GB for the VMs.

I tested Ubuntu 14.04LTS 32-bit on a physical machine with 4GB of RAM and system runs great, no network issues.

The download of 14.04LTS 32-bit does display "for machines running 2GB or less".

How much memory are you giving affected VMs?

[Chris Norris (clnorris)]

Good afternoon MG (heyrastamon),

Thanks for the feedback here. I can confirm that I performed my upgrade to 14.04 in a Hyper-V VM with 4 GB of RAM assigned. When I tried the new installation, I also chose 4 GB for the new VM so got the same networking failure.

I saw the note that the 32-bit download is "for machines running 2GB or less", but as you experienced with 12.04LTS I was also able to use a 4GB VM for some recent versions of 32-bit Ubuntu. Since the memory >2GB was recognized in recent Ubuntu versions, I assumed PAE was in use and that the 2GB constraint listed with the download was deprecated.

I'll go back down to 2 GB temporarily and see if it works, but it definitely seems like there's a legit bug in here somewhere.

[Chris Norris (clnorris)]

Hello Joseph,

I can confirm the bug is present in the 32-bit daily image from your link. I tried the installation using the utopic-desktop-i386.iso image dated 22-May-2014.

The Hyper-V VM where I tried the installation was configured for 4 GB of RAM. MG observed the same issue and was able to clear the problem by reducing the RAM of the VM.

I will try another 32-bit install with the reduced RAM and see if that clears the issue.

[Chris Norris (clnorris)]

Good afternoon,

Wanted to share an observation. When I shut down my 32-bit Hyper-V VM running Ubuntu 14.04 and reduce the memory from 4GB to 2GB, the networking became functional again on the next boot. This confirms MG's observation.

[Joseph Salisbury (jsalisbury)]

Can you see if this bug also affects the latest mainline kernel, which is available from:
http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.16-rc6-utopic/

[MG (heyrastamon)]

Following up on latest kernel, I upgraded kernel on Ubuntu 14.04LTS 32-bit Hyper-V VM with 2GB memory to v3.16-rc6 then increased to memory to 4GB after confirming kernel upgrade. It still experiences network issue/bug. I also tried more recent kernel v3.16-rc7 with the same results. Once the memory is increased, network is disconnected.

Also tested 14.04LTS 32-bit VM with 4GB memory (no kernel upgrade) on VMWare ESXi 5.5. Runs beautifully with no network issues.

[Pakon (pakon)]

I also have issues on a x86_64 system. I can't run the command "apport collect", because it's not installed at this time.
The only way to connect to this system is via a tap-interface. This host is a VPN-Server.

If you need more information, just let me know! :)

[Dexuan Cui (decui)]

This is caused by a bug kernel API used by recent hyper-v synthetic network driver in Ubuntu 14.04 (Ubuntu 13.10 is not affected).

This only affects 32-PAE Linux VM when the VM has more-than-about-4GB memory.

I have fixed the issue:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=d1cd1210834649ce1ca6bafe5ac25d2f40331343

Please pull the fix into the future releases.

[Joseph Salisbury (jsalisbury)]

The patch from Dexuan was included in upstream v3.13.11.11. The latest Ubuntu kernel: 3.13.0-41.70 now has the upstream 3.13.11.11 updates, so this bug should be fixed in Trusty.

Can you test the latest Trusty kernel and confirm that this bug is fixed?

Thanks in advance!

[Jan Marius (jan-marius-t)]

I can confirm that this bug is fixed in Ubuntu 14.04 with the follwing kernel package:
kernel linux-image-3.13.0-43-generic 3.13.0-43.72

Thanks!

[Joseph Salisbury (jsalisbury)]

Marking as "Fix Released" per comment #14. If this bug still exists, please change the status back to "Confirmed".