Index: uspace/srv/fs/fat/fat_fat.c
===================================================================
--- uspace/srv/fs/fat/fat_fat.c	(revision 45df59abc4095939638157c9c4f73004baf03b88)
+++ uspace/srv/fs/fat/fat_fat.c	(revision a6ba0c9cb46c31fab5fccc5ab7ff90a3a8cacb82)
@@ -671,4 +671,6 @@
 	int rc;
 
+	printf("fat_sanity_check() begin\n");
+
 	/* Check number of FATs. */
 	if (bs->fatcnt == 0)
@@ -677,6 +679,10 @@
 	/* Check total number of sectors. */
 
+	printf("fat_sanity_check() totsec\n");
+
 	if (bs->totsec16 == 0 && bs->totsec32 == 0)
 		return ENOTSUP;
+
+	printf("fat_sanity_check() totsec16 vs 32\n");
 
 	if (bs->totsec16 != 0 && bs->totsec32 != 0 &&
@@ -684,11 +690,17 @@
 		return ENOTSUP;
 
+	printf("fat_sanity_check() media descriptor\n");
+
 	/* Check media descriptor. Must be between 0xf0 and 0xff. */
 	if ((bs->mdesc & 0xf0) != 0xf0)
 		return ENOTSUP;
 
+	printf("fat_sanity_check() sec_pre_fat\n");
+
 	/* Check number of sectors per FAT. */
 	if (bs->sec_per_fat == 0)
 		return ENOTSUP;
+
+	printf("fat_sanity_check() root dir size\n");
 
 	/*
@@ -705,16 +717,23 @@
 	/* Check signature of each FAT. */
 
+	printf("fat_sanity_check() FAT signatures\n");
+
 	for (fat_no = 0; fat_no < bs->fatcnt; fat_no++) {
+		printf("fat_sanity_check() read cluster 0\n");
 		rc = fat_get_cluster(bs, devmap_handle, fat_no, 0, &e0);
 		if (rc != EOK)
 			return EIO;
 
+		printf("fat_sanity_check() read cluster 1\n");
 		rc = fat_get_cluster(bs, devmap_handle, fat_no, 1, &e1);
 		if (rc != EOK)
 			return EIO;
 
+		printf("fat_sanity_check() check FAT mdesc\n");
 		/* Check that first byte of FAT contains the media descriptor. */
 		if ((e0 & 0xff) != bs->mdesc)
 			return ENOTSUP;
+
+		printf("fat_sanity_check() e0/e1\n");
 
 		/*
@@ -725,4 +744,5 @@
 			return ENOTSUP;
 	}
+	printf("fat_sanity_check() succeeded\n");
 
 	return EOK;