Intel Wireless-AC 8260 [8086:24f3] Subsystem [8086:1010] - iwlwifi Microcode SW error detected

[Corvus Corax]

Ever since the previous to last apt-get upgrade, my wifi has become very unstable.

After a few minutes to every few hours, the WIFI connection becomes completely unresponsive with any further packets timing out, and any attempt to (re-)connect to any AP being impossible.

Wifi can only be recovered by turning wifi completely off in the menu and back on, or by a system reboot.

System cold reboot after upgrade did not help.

As far as I can recall the bug first appeared with linux-modules-extra-4.15.0-99-generic, but was not present prior to that.

The bug is currently present on the system after apt upgrade to linux-modules-extra-4.15.0-101-generic.

dmesg|grep iwlwifi:
[ 14.623738] iwlwifi 0000:02:00.0: loaded firmware version 34.0.1 op_mode iwlmvm
[ 14.662856] iwlwifi 0000:02:00.0: Detected Intel(R) Dual Band Wireless AC 8260, REV=0x208
[ 14.754145] iwlwifi 0000:02:00.0: base HW address: 28:16:ad:9b:7e:27
[ 14.937064] iwlwifi 0000:02:00.0 wlp2s0: renamed from wlan0
[18635.796270] iwlwifi 0000:02:00.0: Microcode SW error detected. Restarting 0x2000000.
[18635.796433] iwlwifi 0000:02:00.0: Start IWL Error Log Dump:
[18635.796444] iwlwifi 0000:02:00.0: Status: 0x00000100, count: 6
[18635.796452] iwlwifi 0000:02:00.0: Loaded firmware version: 34.0.1
[18635.796462] iwlwifi 0000:02:00.0: 0x00000071 | ADVANCED_SYSASSERT
[18635.796470] iwlwifi 0000:02:00.0: 0x00000230 | trm_hw_status0
[18635.796478] iwlwifi 0000:02:00.0: 0x00000000 | trm_hw_status1
[18635.796486] iwlwifi 0000:02:00.0: 0x0002395C | branchlink2
[18635.796493] iwlwifi 0000:02:00.0: 0x0003867A | interruptlink1
[18635.796500] iwlwifi 0000:02:00.0: 0x0003867A | interruptlink2
[18635.796507] iwlwifi 0000:02:00.0: 0x00000000 | data1
[18635.796515] iwlwifi 0000:02:00.0: 0x00001000 | data2
[18635.796522] iwlwifi 0000:02:00.0: 0x07830000 | data3
[18635.796530] iwlwifi 0000:02:00.0: 0x73C18DA9 | beacon time
[18635.796537] iwlwifi 0000:02:00.0: 0x4816439E | tsf low
[18635.796545] iwlwifi 0000:02:00.0: 0x0000014C | tsf hi
[18635.796552] iwlwifi 0000:02:00.0: 0x00000000 | time gp1
[18635.796559] iwlwifi 0000:02:00.0: 0x55BF8308 | time gp2
[18635.796567] iwlwifi 0000:02:00.0: 0x00000001 | uCode revision type
[18635.796574] iwlwifi 0000:02:00.0: 0x00000022 | uCode version major
[18635.796582] iwlwifi 0000:02:00.0: 0x00000000 | uCode version minor
[18635.796589] iwlwifi 0000:02:00.0: 0x00000201 | hw version
[18635.796596] iwlwifi 0000:02:00.0: 0x00C89008 | board version
[18635.796604] iwlwifi 0000:02:00.0: 0x0000001C | hcmd
[18635.796611] iwlwifi 0000:02:00.0: 0x24022000 | isr0
[18635.796618] iwlwifi 0000:02:00.0: 0x01800000 | isr1
[18635.796625] iwlwifi 0000:02:00.0: 0x08001802 | isr2
[18635.796632] iwlwifi 0000:02:00.0: 0x004178C1 | isr3
[18635.796640] iwlwifi 0000:02:00.0: 0x00000001 | isr4
[18635.796647] iwlwifi 0000:02:00.0: 0x005F019C | last cmd Id
[18635.796654] iwlwifi 0000:02:00.0: 0x00000000 | wait_event
[18635.796662] iwlwifi 0000:02:00.0: 0x00000080 | l2p_control
[18635.796669] iwlwifi 0000:02:00.0: 0x00010030 | l2p_duration
[18635.796676] iwlwifi 0000:02:00.0: 0x0000003F | l2p_mhvalid
[18635.796683] iwlwifi 0000:02:00.0: 0x000000CE | l2p_addr_match
[18635.796691] iwlwifi 0000:02:00.0: 0x0000000D | lmpm_pmg_sel
[18635.796698] iwlwifi 0000:02:00.0: 0x30101341 | timestamp
[18635.796706] iwlwifi 0000:02:00.0: 0x00340818 | flow_handler
[18635.796901] iwlwifi 0000:02:00.0: Start IWL Error Log Dump:
[18635.796909] iwlwifi 0000:02:00.0: Status: 0x00000100, count: 7
[18635.796917] iwlwifi 0000:02:00.0: 0x00100116 | ADVANCED_SYSASSERT
[18635.796924] iwlwifi 0000:02:00.0: 0x00000000 | umac branchlink1
[18635.796932] iwlwifi 0000:02:00.0: 0xC0086A78 | umac branchlink2
[18635.796940] iwlwifi 0000:02:00.0: 0xC0083C90 | umac interruptlink1
[18635.796947] iwlwifi 0000:02:00.0: 0x00000000 | umac interruptlink2
[18635.796954] iwlwifi 0000:02:00.0: 0xDEADBEEF | umac data1
[18635.796961] iwlwifi 0000:02:00.0: 0xDEADBEEF | umac data2
[18635.796969] iwlwifi 0000:02:00.0: 0xDEADBEEF | umac data3
[18635.796976] iwlwifi 0000:02:00.0: 0x00000022 | umac major
[18635.796983] iwlwifi 0000:02:00.0: 0x00000000 | umac minor
[18635.796990] iwlwifi 0000:02:00.0: 0xC0887F60 | frame pointer
[18635.796998] iwlwifi 0000:02:00.0: 0xC0887F60 | stack pointer
[18635.797005] iwlwifi 0000:02:00.0: 0x005F019C | last host cmd
[18635.797012] iwlwifi 0000:02:00.0: 0x00000020 | isr status reg

lsb_release -a
Distributor ID: Ubuntu
Description: Ubuntu 18.04.4 LTS
Release: 18.04
Codename: bionic

uname -a
Linux CorvusMC4 4.15.0-101-generic #102-Ubuntu SMP Mon May 11 10:07:26 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux

apt-cache policy linux-modules-extra-4.15.0-101-generic
linux-modules-extra-4.15.0-101-generic:
  Installed: 4.15.0-101.102
  Candidate: 4.15.0-101.102
  Version table:
 *** 4.15.0-101.102 500
        500 http://de.archive.ubuntu.com/ubuntu bionic-updates/main amd64 Packages
        500 http://security.ubuntu.com/ubuntu bionic-security/main amd64 Packages
        100 /var/lib/dpkg/status

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: linux-modules-extra-4.15.0-101-generic 4.15.0-101.102
ProcVersionSignature: Ubuntu 4.15.0-101.102-generic 4.15.18
Uname: Linux 4.15.0-101-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.14
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: raven 2434 F.... pulseaudio
CurrentDesktop: XFCE
Date: Sun May 24 19:17:14 2020
EcryptfsInUse: Yes
HibernationDevice:
 #RESUME=UUID=de4646dc-eb1a-4530-b6bc-df659b641728
 RESUME=none
InstallationDate: Installed on 2017-04-28 (1122 days ago)
InstallationMedia: Ubuntu 16.04.2 LTS "Xenial Xerus" - Release amd64 (20170215.2)
MachineType: FUJITSU LIFEBOOK E736
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-4.15.0-101-generic root=/dev/mapper/ubuntu--vg-root ro "acpi_osi=!Windows 2012"
RelatedPackageVersions:
 linux-restricted-modules-4.15.0-101-generic N/A
 linux-backports-modules-4.15.0-101-generic N/A
 linux-firmware 1.173.18
SourcePackage: linux
UpgradeStatus: Upgraded to bionic on 2019-06-28 (331 days ago)
dmi.bios.date: 12/20/2016
dmi.bios.vendor: FUJITSU // Insyde Software Corp.
dmi.bios.version: Version 1.22
dmi.board.name: FJNB293
dmi.board.vendor: FUJITSU
dmi.board.version: M4
dmi.chassis.type: 10
dmi.chassis.vendor: FUJITSU
dmi.chassis.version: LIFEBOOK E736
dmi.modalias: dmi:bvnFUJITSU//InsydeSoftwareCorp.:bvrVersion1.22:bd12/20/2016:svnFUJITSU:pnLIFEBOOKE736:pvr10601115935:rvnFUJITSU:rnFJNB293:rvrM4:cvnFUJITSU:ct10:cvrLIFEBOOKE736:
dmi.product.family: LIFEBOOK-FTS
dmi.product.name: LIFEBOOK E736
dmi.product.version: 10601115935
dmi.sys.vendor: FUJITSU

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This change was made by a bot.

[Corvus Corax (corvuscorax)]

After a bit of searching I found this kernel bug which looks related, from last year.
The symptoms are the same, and the error is extremely similar, but for a slightly different chip/firmware combination handled by the same driver

https://bugzilla.kernel.org/show_bug.cgi?id=204167

Therefore I guess it might be one or more of

1 - the same bug, coming to ubuntu delayed
2 - a regression - reintroducing a bug that was previously fixed
3 - a "related/similar bug" reintroducing the same erroneous behaviour on a different firmware/hardware combo

since it seems firmware related, here is my current:

apt-cache policy linux-firmware
linux-firmware:
  Installed: 1.173.18
  Candidate: 1.173.18
  Version table:
 *** 1.173.18 500
        500 http://de.archive.ubuntu.com/ubuntu bionic-updates/main amd64 Packages
        500 http://de.archive.ubuntu.com/ubuntu bionic-updates/main i386 Packages
        500 http://security.ubuntu.com/ubuntu bionic-security/main amd64 Packages
        500 http://security.ubuntu.com/ubuntu bionic-security/main i386 Packages
        100 /var/lib/dpkg/status
     1.173 500
        500 http://de.archive.ubuntu.com/ubuntu bionic/main amd64 Packages
        500 http://de.archive.ubuntu.com/ubuntu bionic/main i386 Packages

[You-Sheng Yang (vicamo)]

Looks like a duplicate of bug 1830192, but it's not. TX A-MSDU was not enabled previously on 4.15.

And, no, it's not a duplicate of https://bugzilla.kernel.org/show_bug.cgi?id=204167, either. This one shows no sign of that at all.

So far I cannot reproduce this with a 8260 chip locally against reported 4.15.0-101-generic connecting to an either 5G or 2.4G WLAN, with or without backport-iwlwifi-dkms installed, even under some stress enable/disable tests.

Could you try install backport-iwlwifi-dkms on your system? Or do you have some more deterministic way to reproduce it?

  $ sudo apt update && sudo apt install backport-iwlwifi-dkms

[Corvus Corax (corvuscorax)]

I do not get any of these Microcode SW error detected errors with backport-iwlwifi-dkms and the wifi is stable.

That being said, I did not encounter any more wifi breakdowns recently. Since they were sporadic to begin with, I cannot say for certain when they stopped happening, but with the current kernel (4.15.0-124-generic) my network connection is pretty stable - even though I still kept getting these "Microcode SW error" messages consistently every once in a while.

With the backport iwlwifi driver there is no such Microcode SW error messages.