WMI function not found

[akil]

Distribution (run cat /etc/os-release):
NAME=Slackware
VERSION="14.2"
ID=slackware
VERSION_ID=14.2
PRETTY_NAME="Slackware 14.2 x86_64 (post 14.2 -current)"
ANSI_COLOR="0;34"
CPE_NAME="cpe:/o:slackware:slackware_linux:14.2"
HOME_URL="http://slackware.com/"
SUPPORT_URL="http://www.linuxquestions.org/questions/slackware-14/"
BUG_REPORT_URL="http://www.linuxquestions.org/questions/slackware-14/"
VERSION_CODENAME=current

Related Application and/or Package Version (run apt policy $PACKAGE NAME):

$ uname -r
5.12.2
$ grep WMI .config
CONFIG_SND_RAWMIDI=m
CONFIG_ACPI_WMI=y
# CONFIG_WMI_BMOF is not set
# CONFIG_HUAWEI_WMI is not set
# CONFIG_INTEL_WMI_SBL_FW_UPDATE is not set
# CONFIG_INTEL_WMI_THUNDERBOLT is not set
# CONFIG_MXM_WMI is not set
# CONFIG_PEAQ_WMI is not set
# CONFIG_XIAOMI_WMI is not set
# CONFIG_ACER_WMI is not set
# CONFIG_ASUS_WMI is not set
# CONFIG_HP_WMI is not set
# CONFIG_MSI_WMI is not set
# CONFIG_TOSHIBA_WMI is not set

Issue/Bug Description:
I cannot build the module, it seems wmi functions is not known from my kernel.

$ make                                                                                                                                                                                                                                    
make -C "/lib/modules/5.12.2-oryp4/build" M="/opt/system76/system76-dkms" modules
make[1]: Entering directory '/usr/src/linux-5.12.2'
  CC [M]  /opt/system76/system76-dkms/system76.o
  MODPOST /opt/system76/system76-dkms/Module.symvers
ERROR: modpost: "param_get_byte" [/opt/system76/system76-dkms/system76.ko] undefined!
ERROR: modpost: "__platform_create_bundle" [/opt/system76/system76-dkms/system76.ko] undefined!
ERROR: modpost: "wmi_has_guid" [/opt/system76/system76-dkms/system76.ko] undefined!
ERROR: modpost: "wmi_remove_notify_handler" [/opt/system76/system76-dkms/system76.ko] undefined!
ERROR: modpost: "wmi_install_notify_handler" [/opt/system76/system76-dkms/system76.ko] undefined!
ERROR: modpost: "pci_assign_unassigned_bus_resources" [/opt/system76/system76-dkms/system76.ko] undefined!
ERROR: modpost: "pci_scan_single_device" [/opt/system76/system76-dkms/system76.ko] undefined!
ERROR: modpost: "param_set_byte" [/opt/system76/system76-dkms/system76.ko] undefined!
ERROR: modpost: "wmi_evaluate_method" [/opt/system76/system76-dkms/system76.ko] undefined!
ERROR: modpost: "ec_transaction" [/opt/system76/system76-dkms/system76.ko] undefined!
make[2]: *** [scripts/Makefile.modpost:132: /opt/system76/system76-dkms/Module.symvers] Error 1
make[2]: *** Deleting file '/opt/system76/system76-dkms/Module.symvers'
make[1]: *** [Makefile:1755: modules] Error 2
make[1]: Leaving directory '/usr/src/linux-5.12.2'
make: *** [Makefile:5: all] Error 2

Steps to reproduce (if you know):
type make

Expected behavior:
Build succeed.

Other Notes:

$ gcc -v
Reading specs from /usr/lib64/gcc/x86_64-slackware-linux/10.3.0/specs
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-slackware-linux/10.3.0/lto-wrapper
Target: x86_64-slackware-linux
Configured with: ../configure --prefix=/usr --libdir=/usr/lib64 --mandir=/usr/man --infodir=/usr/info --enable-shared --enable-bootstrap --enable-languages=ada,brig,c,c++,d,fortran,go,lto,objc,obj-c++ --enable-threads=posix --enable-checking=release --enable-objc-gc --with-system-zlib --enable-libstdcxx-dual-abi --with-default-libstdcxx-abi=new --disable-libstdcxx-pch --disable-libunwind-exceptions --enable-__cxa_atexit --disable-libssp --enable-gnu-unique-object --enable-plugin --enable-lto --disable-install-libiberty --disable-werror --with-gnu-ld --with-isl --verbose --with-arch-directory=amd64 --disable-gtktest --enable-clocale=gnu --disable-multilib --target=x86_64-slackware-linux --build=x86_64-slackware-linux --host=x86_64-slackware-linux
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 10.3.0 (GCC)