At a Gentoo (hardened) I experienced - starting with hardened kernel 4.0.6-r1 - the (attached) hickup of the "03:00.0 Network controller: Intel Corporation Wireless 7260 (rev 83)" at a ThinkPad T440s. The network stucks till I do restart the network device using /etc/init.d/net.wlp3s0.

Whilst it doesn't happen too often :

kern.log-20150628.gz:Jun 28 13:22:14 t44 kernel: [10834.174446] iwlwifi 0000:03:00.0: Microcode SW error detected.  Restarting 0x2000000.
kern.log-20150705.gz:Jun 29 16:51:39 t44 kernel: [  624.439353] iwlwifi 0000:03:00.0: Microcode SW error detected.  Restarting 0x2000000.
kern.log-20150705.gz:Jun 29 17:06:39 t44 kernel: [ 1525.363875] iwlwifi 0000:03:00.0: Microcode SW error detected.  Restarting 0x2000000.
kern.log-20150705.gz:Jun 30 17:33:39 t44 kernel: [36046.223577] iwlwifi 0000:03:00.0: Microcode SW error detected.  Restarting 0x2000000.
kern.log-20150705.gz:Jul  1 21:25:31 t44 kernel: [79159.821177] iwlwifi 0000:03:00.0: Microcode SW error detected.  Restarting 0x2000000.
kern.log-20150713.gz:Jul 11 18:44:12 t44 kernel: [ 1445.297971] iwlwifi 0000:03:00.0: Microcode SW error detected.  Restarting 0x2000000.
kern.log-20150713.gz:Jul 11 18:44:36 t44 kernel: [ 1469.484403] iwlwifi 0000:03:00.0: Microcode SW error detected.  Restarting 0x2000000.
kern.log-20150713.gz:Jul 11 18:45:31 t44 kernel: [ 1524.456420] iwlwifi 0000:03:00.0: Microcode SW error detected.  Restarting 0x2000000.
kern.log-20150713.gz:Jul 12 13:19:15 t44 kernel: [31053.095047] iwlwifi 0000:03:00.0: Microcode SW error detected.  Restarting 0x2000000.
kern.log-20150713.gz:Jul 12 20:10:01 t44 kernel: [55726.004528] iwlwifi 0000:03:00.0: Microcode SW error detected.  Restarting 0x2000000.
kern.log-20150713.gz:Jul 12 23:20:00 t44 kernel: [67138.498066] iwlwifi 0000:03:00.0: Microcode SW error detected.  Restarting 0x2000000.
kern.log:Jul 13 23:35:40 t44 kernel: [42668.521705] iwlwifi 0000:03:00.0: Microcode SW error detected. Restarting 0x2000000.

it is nevertheless annoying.

I tried to switch from sys-kernel/linux-firmware-20150206 to version -20150320 but that doesn't helped.

Any hints where to start ?

-- 
Toralf, pgp key: 872AE508 0076E94E