Index: sys/sys/ata.h
===================================================================
RCS file: /space/ncvs/src/sys/sys/ata.h,v
retrieving revision 1.16
diff -u -r1.16 ata.h
--- sys/sys/ata.h	20 Feb 2003 19:55:45 -0000	1.16
+++ sys/sys/ata.h	19 Mar 2003 22:40:05 -0000
@@ -369,6 +369,7 @@
 #define ATARAIDDELETE		10
 #define ATARAIDSTATUS		11
 #define ATAENCSTAT		12
+#define ATAGMAXCHANNEL		13
 
     union {
 	struct {
@@ -421,6 +422,7 @@
 	    int			error;
 	    char		sense_data[18];
 	} atapi;
+	int			maxchan;
     } u;
 };
 
Index: sys/dev/ata/ata-all.c
===================================================================
RCS file: /space/ncvs/src/sys/dev/ata/ata-all.c,v
retrieving revision 1.172
diff -u -r1.172 ata-all.c
--- sys/dev/ata/ata-all.c	18 Mar 2003 08:45:20 -0000	1.172
+++ sys/dev/ata/ata-all.c	19 Mar 2003 23:14:46 -0000
@@ -304,6 +304,11 @@
     if (cmd != IOCATA)
 	return ENOTTY;
     
+    if (iocmd->cmd == ATAGMAXCHANNEL) {
+	iocmd->u.maxchan = devclass_get_maxunit(ata_devclass);
+	return 0;
+    }
+
     if (iocmd->channel < -1 || iocmd->device < -1 || iocmd->device > SLAVE)
 	return ENXIO;
 
Index: sbin/atacontrol/atacontrol.c
===================================================================
RCS file: /space/ncvs/src/sbin/atacontrol/atacontrol.c,v
retrieving revision 1.19
diff -u -r1.19 atacontrol.c
--- sbin/atacontrol/atacontrol.c	16 Sep 2002 08:34:08 -0000	1.19
+++ sbin/atacontrol/atacontrol.c	19 Mar 2003 23:18:11 -0000
@@ -278,9 +278,17 @@
 	}
 
 	if (!strcmp(argv[1], "list") && argc == 2) {
-		int unit = 0;
+  		struct ata_cmd iocmd;
+		int maxunit, unit;
 
-		while (info_print(fd, unit++, 1) != ENXIO);
+		bzero(&iocmd, sizeof(struct ata_cmd));
+		iocmd.cmd = ATAGMAXCHANNEL;
+		if (ioctl(fd, IOCATA, &iocmd) < 0)
+			err(1, "ioctl");
+
+		maxunit = iocmd.u.maxchan;
+		for (unit = 0; unit < maxunit; unit++)
+			info_print(fd, unit, 1);
 	}
 	else if (!strcmp(argv[1], "info") && argc == 3) {
 		info_print(fd, iocmd.channel, 0);