devmatch: Allow devmatch_blocklist to be set in kenv too

Add in all the variables set in the kenv variable devmatch_blocklist
too. This allows blocking autoloading from the boot loader.

Sponsored by:		Netflix
Reviewed by:		0mp
Differential Revision:	https://reviews.freebsd.org/D32171

libexec/rc/rc.d/devmatch

@@ -64,7 +64,7 @@ devmatch_start()
 	# names with .ko
 
 	devctl freeze
-	x=$(echo '#'${devmatch_blocklist:-${devmatch_blacklist}}'#' | \
+	x=$(echo "#${devmatch_blocklist:-${devmatch_blacklist}}#$(kenv -q devmatch_blocklist)#" | \
 		sed -e "s/ /#/g;s/\.ko#/#/g")
 	for m in ${list}; do
 		m="${m%.ko}"

sbin/devmatch/devmatch.8

@@ -23,7 +23,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd October 12, 2020
+.Dd November 21, 2021
 .Dt DEVMATCH 8
 .Os
 .Sh NAME
@@ -67,6 +67,7 @@ tables with that PNP info can not be found.
 Produce more verbose output.
 .El
 .Sh SEE ALSO
+.Xr rc.conf 5 ,
 .Xr devinfo 8 ,
 .Xr MODULE_PNP_INFO 9
 .Sh HISTORY

share/man/man5/rc.conf.5

@@ -24,7 +24,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd November 18, 2021
+.Dd November 21, 2021
 .Dt RC.CONF 5
 .Os
 .Sh NAME
@@ -261,6 +261,12 @@ disable auto-loading of kernel modules with
 .Pq Vt str
 A whitespace-separated list of kernel modules to be ignored by
 .Xr devmatch 8 .
+In addition, the
+.Xr kenv 1
+.Va devmatch_blocklist
+is appended to this variable to allow disabling of
+.Xr devmatch 8
+loaded modules from the boot loader.
 .It Va devmatch_blacklist
 .Pq Vt str
 This variable is deprecated.