88x2bu-20210702 Linux driver

[vinhnv211]

Hello everyone,

I have WiFi Adaptor using RTL8812 chipset.
From 88x2bu-20210702 driver, I see that it is supported by kernel > 4.19 only.
Driver link: https://github.com/morrownr/88x2bu-20210702

May I know in case I have lower kernel version 3.4. Does this driver work ?

Thank you.

[morrownr]

I have lower kernel version 3.4. Does this driver work ?

It may work. The oldest kernel supported is listed based on several factors:

• Ability to test. My little lab has a few test systems with a variety of distros and kernels but it is impossible to test with everything.
• Generally the oldest kernel supported is based on the oldest kernel that is still supported. Old, unsupported kernels are a security risk.
• You don't say if the 3.4 kernel is a mainline kernel or a modified kernel such as what Red Hat does with RHEL. If it is a RHEL kernel, my answer is no, this driver will not work.

Nick

[vinhnv211]

Thank you Nick,

I compiled 88x2bu-20210702 driver and run in our embedded device (Linux kernel, cross-compiler).

But I got failing by starting hostapd. Like below:
///
...
hw vht capab: 0x0, conf vht capab: 0x3c001a2
Configured VHT capability [VHT_CAP_MAX_MPDU_LENGTH_MASK] exceeds max value supported by the driver (2 > 0)
wlan0: interface state COUNTRY_UPDATE->DISABLED
wlan0: AP-DISABLED
...

Can you please help a look to find this issue ?

My hostapd config:
beacon_int=100
interface=wlan0
driver=nl80211
bridge=br0
ssid=vinhnv_rtk
hw_mode=a
channel=149
max_num_sta=12
ieee80211n=1
ht_capab=[LDPC][HT40+][HT40-][SHORT-GI-20][SHORT-GI-40][MAX-AMSDU-7935]
ieee80211ac=1
vht_capab=[MAX-MPDU-11454][SHORT-GI-80][TX-STBC-2BY1][RX-STBC-1][HTC-VHT][MAX-A-MPDU-LEN-EXP7]
vht_oper_chwidth=1
vht_oper_centr_freq_seg0_idx=155
ieee80211d=1
country_code=US
ieee80211h=1
wpa=2
wpa_key_mgmt=WPA-PSK
wpa_passphrase=1234567890
wpa_pairwise=TKIP CCMP
rsn_pairwise=CCMP
wmm_enabled=1

Best regards,
Vinh

[morrownr]

Hi @vinhnv211

Fun with the compiler I see.

hw vht capab: 0x0, conf vht capab: 0x3c001a2

That leads me to think there is a setting problem:

In the driver directory, run:

$ sudo ./edit-options.sh

This file setting the module parameters (driver options). Look for the options line as it is the only active line in the file. You can scroll down to read the docs but the change I think you need is as follows:

rtw_vht_enable=2

For vht support in AP mode, you need a setting of 2.

Let me know.

Nick

[vinhnv211]

Hi Nick,

No. I read your guidelines carefully and setting rtw_vht_enable=2.

By the way, after checking driver source code, same to be to support VHT kernel version should be greater tham 3.6.0.
As I said before, my kernel version 3.4.
{code}
#if defined(CONFIG_80211AC_VHT) && (LINUX_VERSION_CODE >= KERNEL_VERSION(3, 6, 0))
rtw_cfg80211_init_vht_capab(padapter, &band->vht_cap, BAND_ON_5G, rf_type);
#endif
{code}
Could you pls give me suggestion for this ?

Best regards,
Vinh

[morrownr]

By the way, after checking driver source code, same to be to support VHT kernel version should be greater tham 3.6.0. As I said before, my kernel version 3.4. {code} #if defined(CONFIG_80211AC_VHT) && (LINUX_VERSION_CODE >= KERNEL_VERSION(3, 6, 0)) rtw_cfg80211_init_vht_capab(padapter, &band->vht_cap, BAND_ON_5G, rf_type); #endif {code} Could you pls give me suggestion for this ?

I can give you a suggestion but you are not going to like it:

Upgrade to a newer kernel. I'd recommend at least 4.19 and preferably 5.10. I am contacted periodically to consult with companies or organizations that are building various projects. I can tell you a lot of stories but I will keep it short and get to the point: Kernel 3.2 was released almost 11 years. It hasn't been supported for years and it predates several of the capabilities that are in the driver you are using.

Late last week, a security announcement was made on the Linux wireless subsystem. It involved several parts of the wireless stack. The OpenWRT maintainers had a new version of OpenWRT posted one day later. The well maintained distros are posting updates now, Will those updates go into kernel 3.2?

Something I have learned while using and working on Linux is that there will be problems if you try to use new code with very old code. Linux is under constant work and that work includes updating api's and capabilities. Apps and drivers have to be updated to support the new kernels. It is within reason to keep old apps and drivers working as far back as we have supported kernels but once a kernel is no longer supported, support to keep apps and drivers going on it, goes away. It is a hell of a lot of work.

Your best option if you have a project or product that needs wifi support is to use a kernel that can support the hardware capabilities that you need. It would also be best if you use usb wifi adapters that are supported with in-kernel drivers. Starting with kernel 4.19, there is support for the mt7612u and mt7610u chipsets which give you vht capability.

Nick

[vinhnv211]

Thank you Nick for very detailed answer.

Because of some reasons. I could not updated our kernel to newer version.

From your point of view, any solution to patch vht capability from new version kernel to old version ?

Best regards,
Vinh

[morrownr]

From your point of view, any solution to patch vht capability from new version kernel to old version ?

No, not a practical solution. You could search for a very old version of the rtl8812au driver that says it supports kernel 3.2. That driver, at that time, supported the 8812au and 8811au chipsets which are still available. The 8812bu chipset and this driver are actually a little too modern. I'd have to do some research but even the 8812au may not be practical. vht on an 11 year old kernel, whew!

Nick

[vinhnv211]

Thank you for your information !