Edimax 7811UN first working fine and becomes unusably slow

Hardware Support
1

Hi all,

I have installed Zorin Core on my old MacBook Pro (dual boot) which has a faulty wifi, hence I've been using Edimax 7811UN wifi adapter. The adapter runs fine when I boot to MacOS but is very unstable and unusably slow on Zorin 17.1. It was initially working fine actually and I started having issue with it on day 3 after installing Zorin.

I wonder if there is better driver I could install and use. Here is some output that might help you to help me :slight_smile:

$ sudo lshw -C network

*-network
       description: Wireless interface
       physical id: 8
       bus info: usb@3:1
       logical name: wlx74da388c3b92
       serial: 74:da:38:8c:3b:92
       capabilities: ethernet physical wireless
       configuration: broadcast=yes driver=rtl8192cu driverversion=6.8.0-40-generic firmware=N/A ip=192.168.68.85 link=yes multicast=yes wireless=IEEE 802.11

$ sudo dmesg | grep -i wifi

[    6.916582] rtl8192cu: Loading firmware rtlwifi/rtl8192cufw_TMSC.bin
[  100.687719] UBSAN: array-index-out-of-bounds in /build/linux-hwe-6.8-dKyDY4/linux-hwe-6.8-6.8.0/drivers/net/wireless/realtek/rtlwifi/rtl8192cu/trx.c:502:15
[  100.688097]  rtl_op_tx+0xcc/0xf0 [rtlwifi]

Thank you in advance.

2

Updates. At one point when wifi won't connect at all after laptop went on sleep mode, I got this:

[    6.916582] rtl8192cu: Loading firmware rtlwifi/rtl8192cufw_TMSC.bin
[  100.687719] UBSAN: array-index-out-of-bounds in /build/linux-hwe-6.8-dKyDY4/linux-hwe-6.8-6.8.0/drivers/net/wireless/realtek/rtlwifi/rtl8192cu/trx.c:502:15
[  100.688097]  rtl_op_tx+0xcc/0xf0 [rtlwifi]
[11508.260105] rtl8192cu: Loading firmware rtlwifi/rtl8192cufw_TMSC.bin
[11543.598491] rtl8192cu: Loading firmware rtlwifi/rtl8192cufw_TMSC.bin
[11641.582365] workqueue: rtl_watchdog_wq_callback [rtlwifi] hogged CPU for >10000us 4 times, consider switching to WQ_UNBOUND
[11714.834562] rtl8192cu: Loading firmware rtlwifi/rtl8192cufw_TMSC.bin
3

Welcome to the Forum!

I see You are using the 6.8 Kernel. Please go to the GRUB Menu, click there on ''Advanced Options'' and choose there the 6.5 Kernel to test if it better runs.

1 Like
4

Hi @Ponce-De-Leon thank you for your response. I am using 6.8 kernel. It seems the issue is intermittent, and it was working fine before I switch to 6.5. I think I need to work in 6.5 for a period of time to see if this is more stable.

Just want to ask, should I be concerned over the index out of bound here, which also happens in 6.5

[   19.267568] UBSAN: array-index-out-of-bounds in /build/linux-hwe-6.5-X9ca7v/linux-hwe-6.5-6.5.0/drivers/net/wireless/realtek/rtlwifi/rtl8192cu/trx.c:502:15
5

I wonder if anything here would help you re rtl8192cu wifi.

...but the item is OLD.

Maybe worth a websearch using searchterm: "rtl8192cu ubuntu 22.04"

6

It looks for me that it is an Driver Issue. The Question is: It is a problematic and/or Security relevant Driver Issue ... For this I'm not competent enough.

7

I did try that rtl8192cu driver before I created my post here. But the make process was failed. I think it wasn't compatible.

And after using Kernel 6.5, it seems it is more stable than 6.8. It's good enough for me for now ... so I will keep using 6.5.