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Define the Bootloader Control A/B structure

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Define the A/B structure for implementation using the misc partition
as storage.  The bootloader_control structure is designed to be put in
the bootloader_message slot_suffix field.

Change-Id: I158bdf3e69b3f327a1dde4c6eb1f907dbaf8939c
Signed-off-by: Jeremy Compostella <jeremy.compostella@intel.com>
This commit is contained in:
Jeremy Compostella 2016-04-01 17:16:13 +02:00
parent 71c657a10e
commit b3bf958d4f
1 changed files with 53 additions and 1 deletions
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54
bootloader.h
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@ -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 @@ struct bootloader_message {
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.
*/