Merge "Define the Bootloader Control A/B structure"
am: e6af522
* commit 'e6af5228aa47300e4fe96a0f5068bb344c4b268d':
Define the Bootloader Control A/B structure
Change-Id: I8a66fe124a0c18818485a9e73e742108b3c9d80a
diff --git a/bootloader.h b/bootloader.h
index 742a4ab..92c74f0 100644
--- a/bootloader.h
+++ b/bootloader.h
@@ -45,7 +45,8 @@
* commandline parameter. This is used by fs_mgr to mount /system and
* other partitions with the slotselect flag set in fstab. A/B
* implementations are free to use all 32 bytes and may store private
- * data past the first NUL-byte in this field.
+ * data past the first NUL-byte in this field. It is encouraged, but
+ * not mandatory, to use 'struct bootloader_control' described below.
*/
struct bootloader_message {
char command[32];
@@ -62,6 +63,57 @@
char reserved[192];
};
+#define BOOT_CTRL_MAGIC 0x42414342 /* Bootloader Control AB */
+#define BOOT_CTRL_VERSION 1
+
+struct slot_metadata {
+ // Slot priority with 15 meaning highest priority, 1 lowest
+ // priority and 0 the slot is unbootable.
+ uint8_t priority : 4;
+ // Number of times left attempting to boot this slot.
+ uint8_t tries_remaining : 3;
+ // 1 if this slot has booted successfully, 0 otherwise.
+ uint8_t successful_boot : 1;
+ // Reserved for further use.
+ uint8_t reserved;
+} __attribute__((packed));
+
+/* Bootloader Control AB
+ *
+ * This struct can be used to manage A/B metadata. It is designed to
+ * be put in the 'slot_suffix' field of the 'bootloader_message'
+ * structure described above. It is encouraged to use the
+ * 'bootloader_control' structure to store the A/B metadata, but not
+ * mandatory.
+ */
+struct bootloader_control {
+ // NUL terminated active slot suffix.
+ char slot_suffix[4];
+ // Bootloader Control AB magic number (see BOOT_CTRL_MAGIC).
+ uint32_t magic;
+ // Version of struct being used (see BOOT_CTRL_VERSION).
+ uint8_t version;
+ // Number of slots being managed.
+ uint8_t nb_slot : 3;
+ // Number of times left attempting to boot recovery.
+ uint8_t recovery_tries_remaining : 3;
+ // Ensure 4-bytes alignment for slot_info field.
+ uint8_t reserved0[2];
+ // Per-slot information. Up to 4 slots.
+ struct slot_metadata slot_info[4];
+ // Reserved for further use.
+ uint8_t reserved1[8];
+ // CRC32 of all 28 bytes preceding this field (little endian
+ // format).
+ uint32_t crc32_le;
+} __attribute__((packed));
+
+#if (__STDC_VERSION__ >= 201112L)
+_Static_assert(sizeof(struct bootloader_control) ==
+ sizeof(((struct bootloader_message *)0)->slot_suffix),
+ "struct bootloader_control has wrong size");
+#endif
+
/* Read and write the bootloader command from the "misc" partition.
* These return zero on success.
*/