Test preloaded module,
```
# echo 'compat.linuxkpi.iwlwifi_nvm_file="/tmp/foo"' >> /boot/loader.conf
# echo 'if_iwlwifi_load="YES"' >> /boot/loader.conf
# shutdown -r now
...
# sysctl compat.linuxkpi.iwlwifi_nvm_file
compat.linuxkpi.iwlwifi_nvm_file: /tmp/foo
```
Test dynamically loaded module,
```
# kldunload if_iwlwifi
# kenv -u compat.linuxkpi.iwlwifi_nvm_file
# kldload if_iwlwifi
# sysctl compat.linuxkpi.iwlwifi_nvm_file
compat.linuxkpi.iwlwifi_nvm_file:
```
```
# kldunload if_iwlwifi
# kenv compat.linuxkpi.iwlwifi_nvm_file=/tmp/bar
# kldload if_iwlwifi
# sysctl compat.linuxkpi.iwlwifi_nvm_file
compat.linuxkpi.iwlwifi_nvm_file: /tmp/bar
```
Test with slight modified iwlwifi driver, to verify that CTLFLAG_WR works as intended.
```lang=diff
diff --git a/sys/contrib/dev/iwlwifi/iwl-drv.c b/sys/contrib/dev/iwlwifi/iwl-drv.c
index b99204d87283..2af0bcbb9bdb 100644
--- a/sys/contrib/dev/iwlwifi/iwl-drv.c
+++ b/sys/contrib/dev/iwlwifi/iwl-drv.c
@@ -2025,7 +2025,7 @@ MODULE_PARM_DESC(amsdu_size,
module_param_named(fw_restart, iwlwifi_mod_params.fw_restart, bool, 0444);
MODULE_PARM_DESC(fw_restart, "restart firmware in case of error (default true)");
-module_param_named(nvm_file, iwlwifi_mod_params.nvm_file, charp, 0444);
+module_param_named(nvm_file, iwlwifi_mod_params.nvm_file, charp, 0644);
MODULE_PARM_DESC(nvm_file, "NVM file name");
module_param_named(uapsd_disable, iwlwifi_mod_params.uapsd_disable, uint, 0644);
```
```
# sysctl compat.linuxkpi.iwlwifi_nvm_file="/tmp/nvm_file"
compat.linuxkpi.iwlwifi_nvm_file: /tmp/bar -> /tmp/nvm_file
```