[Lenovo M700z] Wifi malfunctions after updating system

[Taihsiang Ho]

Lenovo M700z (CID 201601-20436) with its pre-installed image.

[Steps To Reproduce]
Enable the proposed pocket, and then update the system by 'sudo apt-get dist-upgrade'

[Expected Result]
Wifi works

[Actual Result]
Wifi malfunctions. The network indicator does not show any wireless AP.

--------

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: linux-image-3.19.0-80-generic 3.19.0-80.88~14.04.1
ProcVersionSignature: Ubuntu 3.19.0-80.88~14.04.1-generic 3.19.8-ckt22
Uname: Linux 3.19.0-80-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.23
Architecture: amd64
Date: Fri Jan 27 01:28:34 2017
DistributionChannelDescriptor:
 # This is a distribution channel descriptor
 # For more information see http://wiki.ubuntu.com/DistributionChannelDescriptor
 canonical-oem-sutton-m700z-trusty-amd64-20160314-0
InstallationDate: Installed on 2017-01-25 (1 days ago)
InstallationMedia: Ubuntu 14.04 "Trusty" - Failed to find casper uuid.conf in 'binary/casper/initrd.img-3.19.0-37-generic.old-dkms' LIVE Binary 20160314-09:31
SourcePackage: linux-lts-vivid
UpgradeStatus: No upgrade log present (probably fresh install)

[Joseph Salisbury (jsalisbury)]

Does the bug go away if you boot into the previous kernel version?

[Taihsiang Ho (tai271828)]

The bug is still there if I boot into the previous kernel version (3.19.0-79.87~14.04.1). However, two weeks ago it did not has this bug with the previous proposed kernel (3.19.0-79.87~14.04.1).

[Brad Figg (brad-figg)]

@taihsiang,

I'd like you to try 2 things:

1. Install the same kernel just like you did and if you have the same failure power the system off and then back on and see if you still have the problem.

2. Test with the lts-xenial kernel and see if you have the same issue.

[Taihsiang Ho (tai271828)]

@brad

1. This issue could reproduce after power-off and back on with the kernel 3.19.0-80-generic #88~14.04.1-Ubuntu

2. This issue could NOT reproduce with the kernel lts-xenial (4.4.0-62-generic #83~14.04.1-Ubuntu)