[R0rt1z2]

Originalmente Escrito por WillyFogg

El bootloader es único, y es el que "decide" qué slot arrancar.
El Recovery suele ser un ramdisk cuando se utilizan slots A/B. De ahí lo que decía en el otro hilo: no entiendo por qué cuando no es capaz de arrancar desde un slot, no lo hace desde el otro.

Saludos

Compi, tú puedes elegir que slot usar vía fastboot pero el problema está en que: Se necesita tener el bootloader desbloqueado.
Esto es lo que pone en la página de ANDROID:

(Click para mostrar/ocultar)

Kernel slot arguments

The current slot suffix should be passed either through a specific device tree (DT) node (/firmware/android/slot_suffix) or through the androidboot.slot_suffix command line argument.
By default, fastboot flashes the current slot on an A/B device. If the update package also contains images for the other, non-current slot, fastboot flashes those images as well. Available options include:

• --slot SLOT. Override the default behavior and prompt fastboot to flash the slot that is passed in as an argument.
• --set-active [SLOT]. Set the slot as active. If no optional argument is specified, then the current slot is set as active.
• fastboot --help. Get details on commands.

If the bootloader implements fastboot, it should support the command set_active <slot> that sets the current active slot to the given slot (this must also clear the unbootable flag for that slot and reset the retry count to default values). The bootloader should also support the following variables:

• has-slot:<partition-base-name-without-suffix>. Returns “yes” if the given partition supports slots, “no” otherwise.
• current-slot. Returns the slot suffix that will be booted from next.
• slot-count. Returns an integer representing the number of available slots. Currently, two slots are supported so this value is 2.
• slot-successful:<slot-suffix>. Returns "yes" if the given slot has been marked as successfully booting, "no" otherwise.
• slot-unbootable:<slot-suffix>. Returns “yes” if the given slot is marked as unbootable, "no" otherwise.
• slot-retry-count. Number of retries remaining to attempt to boot the given slot.

To view all variables, run fastboot getvar all.