diff --git a/sys/amd64/include/vmm_snapshot.h b/sys/amd64/include/vmm_snapshot.h
--- a/sys/amd64/include/vmm_snapshot.h
+++ b/sys/amd64/include/vmm_snapshot.h
@@ -113,6 +113,7 @@
 #define	SNAPSHOT_VAR_OR_LEAVE(DATA, META, RES, LABEL)				\
 	SNAPSHOT_BUF_OR_LEAVE(&(DATA), sizeof(DATA), (META), (RES), LABEL)
 
+#ifndef _KERNEL
 /* compare the value in the meta buffer with the data */
 #define	SNAPSHOT_BUF_CMP_OR_LEAVE(DATA, LEN, META, RES, LABEL)			\
 do {										\
@@ -126,4 +127,5 @@
 #define	SNAPSHOT_VAR_CMP_OR_LEAVE(DATA, META, RES, LABEL)			\
 	SNAPSHOT_BUF_CMP_OR_LEAVE(&(DATA), sizeof(DATA), (META), (RES), LABEL)
 
+#endif	/* _KERNEL */
 #endif
diff --git a/sys/amd64/vmm/vmm_snapshot.c b/sys/amd64/vmm/vmm_snapshot.c
--- a/sys/amd64/vmm/vmm_snapshot.c
+++ b/sys/amd64/vmm/vmm_snapshot.c
@@ -57,7 +57,7 @@
 vm_snapshot_buf(void *data, size_t data_size, struct vm_snapshot_meta *meta)
 {
 	struct vm_snapshot_buffer *buffer;
-	int op;
+	int op, error;
 
 	buffer = &meta->buffer;
 	op = meta->op;
@@ -68,11 +68,14 @@
 	}
 
 	if (op == VM_SNAPSHOT_SAVE)
-		copyout(data, buffer->buf, data_size);
+		error = copyout(data, buffer->buf, data_size);
 	else if (op == VM_SNAPSHOT_RESTORE)
-		copyin(buffer->buf, data, data_size);
+		error = copyin(buffer->buf, data, data_size);
 	else
-		return (EINVAL);
+		error = EINVAL;
+
+	if (error)
+		return (error);
 
 	buffer->buf += data_size;
 	buffer->buf_rem -= data_size;
@@ -98,36 +101,3 @@
 
 	return (length);
 }
-
-int
-vm_snapshot_buf_cmp(void *data, size_t data_size, struct vm_snapshot_meta *meta)
-{
-	struct vm_snapshot_buffer *buffer;
-	int op;
-	int ret;
-
-	buffer = &meta->buffer;
-	op = meta->op;
-
-	if (buffer->buf_rem < data_size) {
-		printf("%s: buffer too small\r\n", __func__);
-		ret = E2BIG;
-		goto done;
-	}
-
-	if (op == VM_SNAPSHOT_SAVE) {
-		ret = 0;
-		copyout(data, buffer->buf, data_size);
-	} else if (op == VM_SNAPSHOT_RESTORE) {
-		ret = memcmp(data, buffer->buf, data_size);
-	} else {
-		ret = EINVAL;
-		goto done;
-	}
-
-	buffer->buf += data_size;
-	buffer->buf_rem -= data_size;
-
-done:
-	return (ret);
-}