UBI: add image sequence number to EC header
An image sequence number is added to the UBI erase-counter header
to be able determine if the root file system contains a mixture
of old and new images (because the flashing failed to complete).
A change to nolo is also needed for this to take effect.
Signed-off-by: Adrian Hunter <adrian.hunter@nokia.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
diff --git a/drivers/mtd/ubi/ubi-media.h b/drivers/mtd/ubi/ubi-media.h
index 8419fdc..503ea9b 100644
--- a/drivers/mtd/ubi/ubi-media.h
+++ b/drivers/mtd/ubi/ubi-media.h
@@ -129,6 +129,7 @@
* @ec: the erase counter
* @vid_hdr_offset: where the VID header starts
* @data_offset: where the user data start
+ * @image_seq: image sequence number
* @padding2: reserved for future, zeroes
* @hdr_crc: erase counter header CRC checksum
*
@@ -144,6 +145,14 @@
* volume identifier header and user data, relative to the beginning of the
* physical eraseblock. These values have to be the same for all physical
* eraseblocks.
+ *
+ * The @image_seq field is used to validate a UBI image that has been prepared
+ * for a UBI device. The @image_seq value can be any value, but it must be the
+ * same on all eraseblocks. UBI will ensure that all new erase counter headers
+ * also contain this value, and will check the value when scanning at start-up.
+ * One way to make use of @image_seq is to increase its value by one every time
+ * an image is flashed over an existing image, then, if the flashing does not
+ * complete, UBI will detect the error when scanning.
*/
struct ubi_ec_hdr {
__be32 magic;
@@ -152,7 +161,8 @@
__be64 ec; /* Warning: the current limit is 31-bit anyway! */
__be32 vid_hdr_offset;
__be32 data_offset;
- __u8 padding2[36];
+ __be32 image_seq;
+ __u8 padding2[32];
__be32 hdr_crc;
} __attribute__ ((packed));