--- /rc/bin/dmaon	Wed Mar 12 03:20:48 2008
+++ /rc/bin/dmaon	Wed Mar 19 23:50:09 2014
@@ -1,7 +1,9 @@
 #!/bin/rc
-# dmaon - turn on ide dma, if possible
+# dmaon [/dev/sd??/ctl ...] - turn on ide dma, if possible
 rfork e
-for (ctl in /dev/sd[C-H]?/ctl)
+if (~ $#* 0)
+	* = /dev/sd[C-H]?/ctl
+for (ctl)
 	if (test -e $ctl && grep -s '^config .* dma ' $ctl &&
 	    ! grep -s '^config (848A|.* dma 00000000 )' $ctl)
 		echo 'dma on' >$ctl