common: android_ab: fix slot suffix for abc block

To align with the official Android BCB (Bootloader Control Block)
specifications, it's important to note that the slot_suffix should start
with an underscore symbol.

For a comprehensive understanding of the expected slot_suffix format in
userspace, please refer to the provided reference [1].

Links:
[1] - https://source.android.com/docs/core/architecture/bootloader/updating#slots

Based-on: https://android-review.googlesource.com/c/platform/external/u-boot/+/1446439
Reviewed-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Guillaume La Roque <glaroque@baylibre.com>
Signed-off-by: Dmitry Rokosov <ddrokosov@salutedevices.com>
Tested-by: Mattijs Korpershoek <mkorpershoek@baylibre.com> # vim3_android
Link: https://lore.kernel.org/r/20241017-android_ab_master-v5-6-43bfcc096d95@salutedevices.com
Signed-off-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>

diff --git a/boot/android_ab.c b/boot/android_ab.c
index c93e51541019d0fe793303c4b3d5286df061906f..a287eac04fe88ad08bdcf1b1b1d6e564d503d800 100644 (file)
--- a/boot/android_ab.c
+++ b/boot/android_ab.c
@@ -52,7 +52,7 @@ static int ab_control_default(struct bootloader_control *abc)
        if (!abc)
                return -EFAULT;
 
-       memcpy(abc->slot_suffix, "a\0\0\0", 4);
+       memcpy(abc->slot_suffix, "_a\0\0", 4);
        abc->magic = BOOT_CTRL_MAGIC;
        abc->version = BOOT_CTRL_VERSION;
        abc->nb_slot = NUM_SLOTS;
@@ -328,7 +328,8 @@ int ab_select_slot(struct blk_desc *dev_desc, struct disk_partition *part_info,
                 * or the device tree.
                 */
                memset(slot_suffix, 0, sizeof(slot_suffix));
-               slot_suffix[0] = BOOT_SLOT_NAME(slot);
+               slot_suffix[0] = '_';
+               slot_suffix[1] = BOOT_SLOT_NAME(slot);
                if (memcmp(abc->slot_suffix, slot_suffix,
                           sizeof(slot_suffix))) {
                        memcpy(abc->slot_suffix, slot_suffix,