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Can CentOS 8 support RTL8188EU Wifi(TL-WN725N USB wifi dongle) by default?

Posted: 2020/07/13 13:42:43
by hyuan
After installing CentOS 8(2004), I can see rtl8188eufw.bin under /lib/firmware/rtlwifi. However by running lsmod, it has no rtl8188eu at all.
I tried lsusb, system can find "Realtek Semiconductor Corp.RTL8188EUS 802.11n Wireless Network Adaptor".

I tried to use tail -f /var/log/messages to see what messages have when I plug out /in TL-WN725N USB wifi dongle, I can see :

USB disconnect, device number 4
new high-speed USB device number 5 using ehci-pci
new USB device found, idVendor=0bda, idProduct=8179, bcdDevice= 0.00
New USB device strings: Mfr=1, Product=2,SerialNumber=3
Product: 802.11n NIC
Manuafacturer: Realtek
SerialNumber: 00E04C0001


using ifconfig -a to see if system can recognize wlan adaptor, it has nothing about wlan in command output.

Then I tried using insmod /lib/firmware/rtlwifi/rtl8188eufw.bin to manually load module, it shows error of:
insmod: ERROR: could not insert module /lib/firmware/rtlwifi/rtl8188eufw.bin: Invalid module format

Can anybody point to me if CentOS8(2004) has already supported RTL8188EU wifi adapter driver or not? If yes, why system can't recognize the hardware and load module automatically? Shall I manually build/compile/install it from: https://github.com/lwfinger/rtl8188eu ?

Thanks

Re: Can CentOS 8 support RTL8188EU Wifi(TL-WN725N USB wifi dongle) by default?

Posted: 2020/07/13 15:31:46
by TrevorH
Could you please stick to one thread for this. I see 4 posts by you across 3 different forums and they are all for the same thing. Post once, stick to that thread.

Did you ask ELRepo about it yet?

Re: Can CentOS 8 support RTL8188EU Wifi(TL-WN725N USB wifi dongle) by default?

Posted: 2020/07/14 15:21:18
by hyuan
ELRepo has only drivers for CentOS7:
https://centos.pkgs.org/7/elrepo-x86_64 ... 4.rpm.html
https://mirror.rackspace.com/elrepo/elr ... x86_64.rpm
tried to use rpm above, it is failed to install because kernel is not compatible.

trying to re-build the driver from source code(https://github.com/lwfinger/rtl8188eu) under centos 8.2(2004), it is failed because kernel back port changes by CentOS. Need to debug for it.

Re: Can CentOS 8 support RTL8188EU Wifi(TL-WN725N USB wifi dongle) by default?

Posted: 2020/07/14 16:19:15
by TrevorH
I am aware of what drivers ELRepo has at the moment but the point is, raise an RFE and ask them if they will build it.

Re: Can CentOS 8 support RTL8188EU Wifi(TL-WN725N USB wifi dongle) by default?

Posted: 2020/07/15 12:57:16
by hyuan
ELRepo has no respone for my request. :-(

So I tried to modify some code((https://github.com/lwfinger/rtl8188eu) and built the driver moduble by my own. However met below issue when loading module:

[ 177.003060] usb 2-1.4: new high-speed USB device number 4 using ehci-pci
[ 177.081890] usb 2-1.4: New USB device found, idVendor=0bda, idProduct=8179, bcdDevice= 0.00
[ 177.081894] usb 2-1.4: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 177.081896] usb 2-1.4: Product: 802.11n NIC
[ 177.081897] usb 2-1.4: Manufacturer: Realtek
[ 177.081899] usb 2-1.4: SerialNumber: 00E04C0001
[ 177.567475] 8188eu: loading out-of-tree module taints kernel.
[ 177.567907] 8188eu: module verification failed: signature and/or required key missing - tainting kernel
[ 177.568037] 8188eu: Unknown symbol iwe_stream_add_event (err 0)
[ 177.568137] 8188eu: Unknown symbol wireless_send_event (err 0)
[ 177.568177] 8188eu: Unknown symbol iwe_stream_add_point (err 0)
[ 346.976147] 8188eu: Unknown symbol iwe_stream_add_event (err 0)
[ 346.976244] 8188eu: Unknown symbol wireless_send_event (err 0)
[ 346.976283] 8188eu: Unknown symbol iwe_stream_add_point (err 0)

is there any way to sign the compiled module file (8181eu.ko) so centos8 system can load the module?

Re: Can CentOS 8 support RTL8188EU Wifi(TL-WN725N USB wifi dongle) by default?

Posted: 2020/07/15 13:40:25
by jlehtone
The lack of signature is not a game-stopper.

For example, NVidia's kernel module compiled by ELRepo gives me:
nvidia: module verification failed: signature and/or required key missing - tainting kernel
Yet, it is functional. (There is a way to add keys, but do I bother? No.)

Re: Can CentOS 8 support RTL8188EU Wifi(TL-WN725N USB wifi dongle) by default?

Posted: 2020/07/17 15:40:27
by hyuan
Thanks, I have addtional question:

Is standard CentOS 8 release the compiled kernel provides wireless (802.11) support? Should I need to "make menuconfig" to select enable options like
CONFIG_WIRELESS/CONFIG_WILRESS_EXT/CONFIG_WEXT_PRIV and re-compile kernel to so system can load my driver module. Because I found dmesg below when I insert my usb wifi dongle:

[ 346.976147] 8188eu: Unknown symbol iwe_stream_add_event (err 0)
[ 346.976244] 8188eu: Unknown symbol wireless_send_event (err 0)
[ 346.976283] 8188eu: Unknown symbol iwe_stream_add_point (err 0)


It seems kernel is loading driver module but can't find symbol from kernal for above ?

Thanks

Re: Can CentOS 8 support RTL8188EU Wifi(TL-WN725N USB wifi dongle) by default?

Posted: 2020/07/17 17:52:54
by TrevorH
Looks like you built it against a kernel version that you are not now running. That's the drawback to building it yourself, you will have to do every time the kernel gets updated - on average so far this year, at least once a month. Your kernel version and kernel-devel/-headers version must match exactly to the last digit. And you have to rebuild it each time you dnf update and get a newer kernel.

ELRepo doesn't suffer from this problem. or at least it does but only at point release times.

Re: Can CentOS 8 support RTL8188EU Wifi(TL-WN725N USB wifi dongle) by default?

Posted: 2020/07/18 01:17:09
by hyuan
No, I am building driver module at the same PC, kernel is same as centos 8.2(2004) : 4.18.0-193.

Just curious why kernel can't locate these symbols when loading my usb WiFi driver module. Please note these symbols belong to original linux kernel, not part of driver. They are routines of wext middleware, original source code is under kernel source tree of net/wireless/wext_core.c

Relevant packages you mentioned I had installed with USB disk by rpm, before I can make my usb WiFi dongle work with this PC(by compiling it's driver source code), this PC will not have Internet access, so dnf/yum will not work.

Re: Can CentOS 8 support RTL8188EU Wifi(TL-WN725N USB wifi dongle) by default?

Posted: 2020/07/18 01:19:30
by TrevorH
The current CentOS 8 kernel is 4.18.0-193.6.3.el8_2.x86_64 so if you built for 4.18.0-193 then that explains the missing symbols.