[SOLVED] (was Intel VT/iommu error) Debian + Asus N550JV + Atheros AR9485 = painfully slow wifi

[fu7zed]

Hi,

I’ve installed Debian 11 on my Asus N550JV and can’t get the wifi to work properly.

The problem :
I can connect using the NetworkManager Applet from the tray icon in XFCE, but the signal works properly only to 5 to 10 seconds, until it reduces to a point I can't even ping a website.

Until now, I used Ubuntu derivatives or Arch on this computer, and wifi connection always worked without any tweaks.

The laptop has an Atheros AR9485 Wireless Network Adapter, running the ath9k driver

Code: Select all

sudo lshw -class network
  *-network
       description: Interface réseau sans fil
       produit: AR9485 Wireless Network Adapter
       fabriquant: Qualcomm Atheros
       identifiant matériel: 0
       information bus: pci@0000:04:00.0
       nom logique: wlp4s0
       version: 01
       numéro de série: 24:0a:64:63:bc:43
       bits: 64 bits
       horloge: 33MHz
       fonctionnalités: pm msi pciexpress bus_master cap_list rom ethernet physical wireless
       configuration: broadcast=yes driver=ath9k driverversion=5.16.0-3-amd64 firmware=N/A ip=192.168.1.13 latency=0 link=yes multicast=yes wireless=IEEE 802.11
       ressources: irq:18 mémoire:f7900000-f797ffff mémoire:f7980000-f798ffff
  *-network
       description: Ethernet interface
       produit: RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller
       fabriquant: Realtek Semiconductor Co., Ltd.
       identifiant matériel: 0
       information bus: pci@0000:05:00.0
       nom logique: enp5s0
       version: 0c
       numéro de série: 74:d0:2b:b7:a4:19
       capacité: 1Gbit/s
       bits: 64 bits
       horloge: 33MHz
       fonctionnalités: pm msi pciexpress msix vpd bus_master cap_list ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd 1000bt-fd autonegotiation
       configuration: autonegotiation=on broadcast=yes driver=r8169 driverversion=5.16.0-3-amd64 firmware=rtl8168g-2_0.0.1 02/06/13 latency=0 link=no multicast=yes port=twisted pair
       ressources: irq:19 portE/S:d000(taille=256) mémoire:f7800000-f7800fff mémoire:f2100000-f2103fff

What I tried :

1)
I installed debian using the default iso (debian-11.2.0-amd64-netinst.iso).
As I ran into the problem during the installation (unable to download necessary packages), I admitted that even if I was able to connect, maybe I was needing something from the non-free repos.

2)
I tried another install, this time the dirty way with the non-free XFCE live iso (debian-live-11.2.0-amd64-xfce+nonfree.iso).
Still having the wifi bug, but I could at least finish the installation.

Anyway, now I don’t think it could be a proprietary firmware issue, as the `ath9k` driver is included in the kernel https://cateee.net/lkddb/web-lkddb/ATH9K.html

3)
I’ve seen a lot of forum posts about tweaking the params of `/etc/modprobe.d/ath9k.conf`, especially the `nohwcrypt=1` param.
(full list of available params here https://github.com/reynhout/chrx/blob/m ... ath9k.conf)
I tried a bit of everything, didn’t fix.

4)
I’ve found this article, about replacing network-manager with `wicd` …
http://pkill-9.com/2013/04/23/stabilizi ... ux-wheezy/
but `wicd` is not maintained anymore and has been kicked out of the debian repos.

5)
I tried to compile a backported driver, as described here :
https://ubuntuforums.org/showthread.php ... st12890183
The driver compiled successfully.
But didn´t fix.

6)
I wondered if my bug would be fixed in a recent kernel, so I decided to take a turn for the worse and upgraded to Sid.

Code: Select all

cat /proc/version
Linux version 5.16.0-3-amd64 (debian-kernel@lists.debian.org) (gcc-11 (Debian 11.2.0-18) 11.2.0, GNU ld (GNU Binutils for Debian) 2.38) #1 SMP PREEMPT Debian 5.16.11-1 (2022-02-25)

I am now running a shiny new 5.16 kernel.
Didn’t fix either.

7)
As I was running out of troubleshooting ideas, I installed other distributions aside to check if my hardware is faulty, or if they would include specific configuration or hint for a fix.
- MX Linux : same bug
- Manjaro : works
- Linux Mint : works
- Ubuntu : works
- Fedora : works
(currently : Triple Boot Debian Sid XFCE / Xubuntu 21.10 XFCE / Fedora 35 XFCE)
It seems like only Debian and direct derivatives would be impacted by the problem on my machine.

The `/etc/modprobe.d/` is stacked with config files on the other distributions (mostly blacklisting stuff), but nothing related with the ath9k driver.

Most config files, like `/etc/resolv.conf` have exactly the same contents in each distribution, and I have a hard time trying to understand what is going on.

Any tip would be highly appreciated !

[sunrat]

firmware=N/A

Maybe needs firmware-atheros installed
Some wifi chips have issues with power saving mode. Search for how to disable it.

[4D696B65]

This happened long ago to me, maybe the problem is similar.
viewtopic.php?p=364733#p364733

[fu7zed]

Hi, and thanks for your answers !

I just tried to set `/etc/modprobe.d/ath9k.conf` with the following options:

Code: Select all

options ath9k nohwcrypt=1 ps_enable=0

According to your recommendations and the docs, it should disable hardware encryption and disable WLAN PowerSave.

But nothing changes (upon reboot or `sudo modprobe -r ath9k && sudo modprobe ath9k`).

--

I think I will dig further on the `firmware=N/A` issue.

This is weird, as synaptic says these two firmwares are already installed :

• firmware-ath9k-htc (from main)

• firmware-atheros (from non-free)

Even weirder is that it works under Ubuntu and Fedora with the same `firmware=N/A` output :

Ubuntu :

Code: Select all

  *-network
       description: Interface réseau sans fil
       produit: AR9485 Wireless Network Adapter
       fabricant: Qualcomm Atheros
       identifiant matériel: 0
       information bus: pci@0000:04:00.0
       nom logique: wlp4s0
       version: 01
       numéro de série: 24:0a:64:63:bc:43
       bits: 64 bits
       horloge: 33MHz
       fonctionnalités: pm msi pciexpress bus_master cap_list rom ethernet physical wireless
       configuration : broadcast=yes driver=ath9k driverversion=5.13.0-30-generic firmware=N/A ip=192.168.1.13 latency=0 link=yes multicast=yes wireless=IEEE 802.11
       ressources : irq:18 mémoire:f7900000-f797ffff mémoire:f7980000-f798ffff

Fedora :

Code: Select all

  *-network                 
       description: Wireless interface
       product: AR9485 Wireless Network Adapter
       vendor: Qualcomm Atheros
       physical id: 0
       bus info: pci@0000:04:00.0
       logical name: wlp4s0
       version: 01
       serial: 24:0a:64:63:bc:43
       width: 64 bits
       clock: 33MHz
       capabilities: pm msi pciexpress bus_master cap_list rom ethernet physical wireless
       configuration: broadcast=yes driver=ath9k driverversion=5.16.11-200.fc35.x86_64 firmware=N/A ip=192.168.1.13 latency=0 link=yes multicast=yes wireless=IEEE 802.11
       resources: irq:18 memory:f7900000-f797ffff memory:f7980000-f798ffff

[fu7zed]

I finally fixed it !

There was a looping error message in the logs:

Code: Select all

sudo dmesg
...
[  488.032111] ath: phy0: DMA failed to stop in 10 ms AR_CR=0x00000024 AR_DIAG_SW=0x02000020 DMADBG_7=0x00006100
[  489.200480] wlp4s0: authenticate with a4:3e:51:bc:bf:76
[  489.220944] wlp4s0: send auth to a4:3e:51:bc:bf:76 (try 1/3)
[  489.222922] wlp4s0: authenticated
[  489.223321] wlp4s0: associate with a4:3e:51:bc:bf:76 (try 1/3)
[  489.227577] wlp4s0: RX AssocResp from a4:3e:51:bc:bf:76 (capab=0x1411 status=0 aid=1)
[  489.227686] wlp4s0: associated
[  489.227751] ath: EEPROM regdomain: 0x80fa
[  489.227751] ath: EEPROM indicates we should expect a country code
[  489.227752] ath: doing EEPROM country->regdmn map search
[  489.227753] ath: country maps to regdmn code: 0x37
[  489.227754] ath: Country alpha2 being used: FR
[  489.227755] ath: Regpair used: 0x37
[  489.227756] ath: regdomain 0x80fa dynamically updated by country element
[  489.281060] wlp4s0: Limiting TX power to 20 (20 - 0) dBm as advertised by a4:3e:51:bc:bf:76
...

I have found a related entry here :
https://wiki.archlinux.org/title/Networ ... s#Cause_#5

My bug was related to Intel VT (Virtualization Technology).
I still don't understand why and how it would mess with a physical device, but it did.

I've found two ways to make it work :

1)
In the BIOS, disable the VT-d entry

OR

2)
Disable the Intel IOMMU driver in the kernel boot parameters:
- open `/etc/default/grub`
- find the `GRUB_CMDLINE_LINUX_DEFAULT` option and append `intel_iommu=off` at the end of the parameters list
example :

Code: Select all

GRUB_CMDLINE_LINUX_DEFAULT="quiet intel_iommu=off"

So far, I'm not sure about the side effects this tweak will have.
I'll try to create a VM to see if I find noticeable problems.

Many thanks sunrat and 4D696B65 for helping me !