Index: stand/common/devopen.c
===================================================================
--- stand/common/devopen.c
+++ stand/common/devopen.c
@@ -28,6 +28,7 @@
 __FBSDID("$FreeBSD$");
 
 #include <stand.h>
+#include <assert.h>
 #include <string.h>
 
 #include "bootstrap.h"
@@ -37,14 +38,37 @@
 #endif
 
 int
-devopen(struct open_file *f, const char *fname, const char **file) 
+devopen(struct open_file *f, const char *fname, const char **file,
+    struct devdesc *odev)
 {
 	struct devdesc *dev;
 	int result;
 
-	result = archsw.arch_getdev((void **)&dev, fname, file);
-	if (result)
-		return (result);
+	dev = NULL;
+	if (odev == NULL || (*fname != '/' && strchr(fname, ':') != NULL)) {
+		/*
+		 * If we weren't passed a device to open on, or if we were
+		 * passed a filename that looks like it could have another
+		 * device specified, then we'll extract that.
+		 */
+		result = archsw.arch_getdev((void **)&dev, fname, file);
+		if (result)
+			return (result);
+	}
+
+	if (dev == NULL) {
+		/*
+		 * We must have had an open device passed to us and the above
+		 * arch_getdev() didn't happen.  Each file is assumed to have a
+		 * distinct f_devdata that it's OK to free, so grab a copy.
+		 */
+		assert(odev != NULL);
+		dev = malloc(odev->d_size);
+		if (dev == NULL)
+			return (ENOMEM);
+		memcpy(dev, odev, odev->d_size);
+		*file = fname;
+	}
 
 	/* point to device-specific data so that device open can use it */
 	f->f_dev = dev->d_dev;
Index: stand/libsa/gzipfs.c
===================================================================
--- stand/libsa/gzipfs.c
+++ stand/libsa/gzipfs.c
@@ -181,7 +181,7 @@
     sprintf(zfname, "%s.gz", fname);
 
     /* Try to open the compressed datafile */
-    rawfd = open(zfname, O_RDONLY);
+    rawfd = open_ondev(zfname, O_RDONLY, (struct devdesc *)f->f_devdata);
     free(zfname);
     if (rawfd == -1)
 	return(ENOENT);
Index: stand/libsa/open.c
===================================================================
--- stand/libsa/open.c
+++ stand/libsa/open.c
@@ -138,7 +138,7 @@
 }
 
 int
-open(const char *fname, int mode)
+open_ondev(const char *fname, int mode, struct devdesc *dev)
 {
 	struct fs_ops *fs;
 	struct open_file *f;
@@ -167,7 +167,7 @@
 		goto err;
 	}
 
-	error = devopen(f, fname, &file);
+	error = devopen(f, fname, &file, dev);
 	if (error ||
 	    (((f->f_flags & F_NODEV) == 0) && f->f_dev == NULL))
 		goto err;
@@ -209,3 +209,10 @@
 	TSEXIT();
 	return (fd);
 }
+
+int
+open(const char *fname, int mode)
+{
+
+	return (open_ondev(fname, mode, NULL));
+}
Index: stand/libsa/stand.h
===================================================================
--- stand/libsa/stand.h
+++ stand/libsa/stand.h
@@ -291,6 +291,7 @@
 
 extern int	mount(const char *dev, const char *path, int flags, void *data);
 extern int	unmount(const char *dev, int flags);
+extern int	open_ondev(const char *, int, struct devdesc *);
 extern int	open(const char *, int);
 #define	O_RDONLY	0x0
 #define O_WRONLY	0x1
@@ -412,7 +413,8 @@
 extern int		getchar(void);
 extern int		ischar(void);
 extern void		putchar(int);
-extern int		devopen(struct open_file *, const char *, const char **);
+extern int		devopen(struct open_file *, const char *, const char **,
+    struct devdesc *);
 extern int		devclose(struct open_file *f);
 extern void		panic(const char *, ...) __dead2 __printflike(1, 2);
 extern void		panic_action(void) __weak_symbol __dead2;