That’s just one of many issues with the OSMC headers, which still seem to be broken.
Please run the workaround mentioned here: Has anybody tried to install Wireguard? - #28 by dillthedog
It then compiles successfully – though no guarantees it’ll work, of course:
osmc@osmc:~/Downloads/rtl88x2BU_WiFi_linux_v5.3.1_27678.20180430_COEX20180427-5959$ modinfo ./8812bu.ko
filename: /home/osmc/Downloads/rtl88x2BU_WiFi_linux_v5.3.1_27678.20180430_COEX20180427-5959/./8812bu.ko
version: v5.3.1_27678.20180430_COEX20180427-5959
author: Realtek Semiconductor Corp.
description: Realtek Wireless Lan Driver
license: GPL
srcversion: 49D451124CBE237914609CA
alias: usb:v0B05p184Cd*dc*dsc*dp*icFFiscFFipFFin*
alias: usb:v0B05p1841d*dc*dsc*dp*icFFiscFFipFFin*
alias: usb:v7392pC822d*dc*dsc*dp*icFFiscFFipFFin*
alias: usb:v7392pB822d*dc*dsc*dp*icFFiscFFipFFin*
alias: usb:v2357p0115d*dc*dsc*dp*icFFiscFFipFFin*
alias: usb:v2001p331Cd*dc*dsc*dp*icFFiscFFipFFin*
alias: usb:v13B1p0043d*dc*dsc*dp*icFFiscFFipFFin*
alias: usb:v0BDApB812d*dc*dsc*dp*icFFiscFFipFFin*
alias: usb:v0BDApB82Cd*dc*dsc*dp*icFFiscFFipFFin*
depends: cfg80211
name: 8812bu
vermagic: 4.19.55-6-osmc SMP preempt mod_unload modversions ARMv7 p2v8
parm: rtw_ips_mode:The default IPS mode (int)
parm: rtw_lps_level:The default LPS level (int)
parm: rtw_usb_rxagg_mode:int
parm: rtw_dynamic_agg_enable:int
parm: rtw_drv_log_level:set log level when insert driver module, default log level is _DRV_INFO_ = 4 (uint)
parm: rtw_tx_bw_mode:The max tx bw for 2.4G and 5G. format is the same as rtw_bw_mode (uint)
parm: rtw_rx_ampdu_sz_limit_1ss:RX AMPDU size limit for 1SS link of each BW, 0xFF: no limitation (array of uint)
parm: rtw_rx_ampdu_sz_limit_2ss:RX AMPDU size limit for 2SS link of each BW, 0xFF: no limitation (array of uint)
parm: rtw_rx_ampdu_sz_limit_3ss:RX AMPDU size limit for 3SS link of each BW, 0xFF: no limitation (array of uint)
parm: rtw_rx_ampdu_sz_limit_4ss:RX AMPDU size limit for 4SS link of each BW, 0xFF: no limitation (array of uint)
parm: rtw_vht_enable:int
parm: rtw_vht_rx_mcs_map:VHT RX MCS map (uint)
parm: rtw_rf_config:int
parm: rtw_country_code:The default country code (in alpha2) (charp)
parm: rtw_channel_plan:The default chplan ID when rtw_alpha2 is not specified or valid (int)
parm: rtw_excl_chs:exclusive channel array (array of uint)
parm: rtw_qos_opt_enable:int
parm: ifname:The default name to allocate for first interface (charp)
parm: if2name:The default name to allocate for second interface (charp)
parm: rtw_pwrtrim_enable:int
parm: rtw_initmac:charp
parm: rtw_special_rf_path:int
parm: rtw_chip_version:int
parm: rtw_rfintfs:int
parm: rtw_lbkmode:int
parm: rtw_network_mode:int
parm: rtw_channel:int
parm: rtw_mp_mode:int
parm: rtw_wmm_enable:int
parm: rtw_vrtl_carrier_sense:int
parm: rtw_vcs_type:int
parm: rtw_busy_thresh:int
parm: rtw_ht_enable:int
parm: rtw_bw_mode:int
parm: rtw_ampdu_enable:int
parm: rtw_rx_stbc:int
parm: rtw_rx_ampdu_amsdu:int
parm: rtw_tx_ampdu_amsdu:int
parm: rtw_beamform_cap:int
parm: rtw_lowrate_two_xmit:int
parm: rtw_power_mgnt:int
parm: rtw_smart_ps:int
parm: rtw_low_power:int
parm: rtw_wifi_spec:int
parm: rtw_full_ch_in_p2p_handshake:int
parm: rtw_antdiv_cfg:int
parm: rtw_antdiv_type:int
parm: rtw_drv_ant_band_switch:int
parm: rtw_single_ant_path:int
parm: rtw_switch_usb_mode:int
parm: rtw_enusbss:int
parm: rtw_hwpdn_mode:int
parm: rtw_hwpwrp_detect:int
parm: rtw_hw_wps_pbc:int
parm: rtw_check_hw_status:int
parm: rtw_max_roaming_times:The max roaming times to try (uint)
parm: rtw_mc2u_disable:int
parm: rtw_advnace_ota:int
parm: rtw_notch_filter:0:Disable, 1:Enable, 2:Enable only for P2P (uint)
parm: rtw_hiq_filter:0:allow all, 1:allow special, 2:deny all (uint)
parm: rtw_adaptivity_en:0:disable, 1:enable (uint)
parm: rtw_adaptivity_mode:0:normal, 1:carrier sense (uint)
parm: rtw_adaptivity_dml:0:disable, 1:enable (uint)
parm: rtw_adaptivity_dc_backoff:DC backoff for Adaptivity (uint)
parm: rtw_adaptivity_th_l2h_ini:th_l2h_ini for Adaptivity (int)
parm: rtw_adaptivity_th_edcca_hl_diff:th_edcca_hl_diff for Adaptivity (int)
parm: rtw_amplifier_type_2g:BIT3:2G ext-PA, BIT4:2G ext-LNA (uint)
parm: rtw_amplifier_type_5g:BIT6:5G ext-PA, BIT7:5G ext-LNA (uint)
parm: rtw_RFE_type:default init value:64 (uint)
parm: rtw_powertracking_type:default init value:64 (uint)
parm: rtw_GLNA_type:default init value:0 (uint)
parm: rtw_TxBBSwing_2G:default init value:0xFF (uint)
parm: rtw_TxBBSwing_5G:default init value:0xFF (uint)
parm: rtw_OffEfuseMask:default open Efuse Mask value:0 (uint)
parm: rtw_FileMaskEfuse:default drv Mask Efuse value:0 (uint)
parm: rtw_rxgain_offset_2g:default RF Gain 2G Offset value:0 (uint)
parm: rtw_rxgain_offset_5gl:default RF Gain 5GL Offset value:0 (uint)
parm: rtw_rxgain_offset_5gh:uint
parm: rtw_rxgain_offset_5gm:default RF Gain 5GM Offset value:0 (uint)
parm: rtw_pll_ref_clk_sel:force pll_ref_clk_sel, 0xF:use autoload value (uint)
parm: rtw_tx_pwr_by_rate:0:Disable, 1:Enable, 2: Depend on efuse (int)
parm: rtw_target_tx_pwr_2g_a:2.4G target tx power (unit:dBm) of RF path A for each rate section, should match the real calibrate power, -1: undefined (array of int)
parm: rtw_target_tx_pwr_2g_b:2.4G target tx power (unit:dBm) of RF path B for each rate section, should match the real calibrate power, -1: undefined (array of int)
parm: rtw_target_tx_pwr_2g_c:2.4G target tx power (unit:dBm) of RF path C for each rate section, should match the real calibrate power, -1: undefined (array of int)
parm: rtw_target_tx_pwr_2g_d:2.4G target tx power (unit:dBm) of RF path D for each rate section, should match the real calibrate power, -1: undefined (array of int)
parm: rtw_target_tx_pwr_5g_a:5G target tx power (unit:dBm) of RF path A for each rate section, should match the real calibrate power, -1: undefined (array of int)
parm: rtw_target_tx_pwr_5g_b:5G target tx power (unit:dBm) of RF path B for each rate section, should match the real calibrate power, -1: undefined (array of int)
parm: rtw_target_tx_pwr_5g_c:5G target tx power (unit:dBm) of RF path C for each rate section, should match the real calibrate power, -1: undefined (array of int)
parm: rtw_target_tx_pwr_5g_d:5G target tx power (unit:dBm) of RF path D for each rate section, should match the real calibrate power, -1: undefined (array of int)
parm: rtw_phy_file_path:The path of phy parameter (charp)
parm: rtw_load_phy_file:PHY File Bit Map (int)
parm: rtw_decrypt_phy_file:Enable Decrypt PHY File (int)
parm: rtw_dynamic_soml_en:0: disable, 1: enable with default param, 2: enable with specified param. (int)
parm: rtw_dynamic_soml_train_num:SOML training number (int)
parm: rtw_dynamic_soml_interval:SOML training interval (int)
parm: rtw_dynamic_soml_period:SOML training period (int)
parm: rtw_dynamic_soml_delay:SOML training delay (int)
parm: rtw_en_napi:int
parm: rtw_en_gro:int
parm: rtw_iqk_fw_offload:int
parm: rtw_ch_switch_offload:int