BOOT_ACK (EXT_CSD, bit 6) must be set in the device, or the BROM will not boot from the partition. If it finds a boot partition to be enabled in bits (either a 1 or a 2 in there, selecting one of the two boot partitions), it will try to boot from the first sectors of that selected boot partition, following the usual eGON boot protocol. The BROM seems to follow the eMMC boot specification, the only restriction is the limited set of supported eMMC boot timing/width configurations.Īfter checking for valid boot signatures on the SD card (SDC0), the BROM will check the eMMC boot partition configuration in EXT_CSD (if it finds an eMMC device on SDC2). The following information has been gained by experimentation and observation (on the A64) and has not been yet verified by examining BROM code. The JEDEC eMMC spec mentions "boot operation" and "alternative boot operation".
#Allwinner a33 bootloader manual
They are not sharing the same block device with the data.Īt least Allwinner H3 is expected to support eMMC boot paritions because the manual says "Supports eMMC boot operation and alternative boot operation". But if you are happy with this particular setup, then just go to the Bootable SD card page for further information and instructions.ĮMMC supports separate boot partitions for storing the bootloader. And the first stage bootloader (U-Boot SPL or Allwinner's boot0) is expected to be stored in a special hardcoded place between the MBR and the first partition, which does not play very nice with GPT partitioning.
#Allwinner a33 bootloader full
Which means that it can be treated as a single large block device representing its full capacity. 4 Installing mainline U-Boot in a boot partitionįirst of all, any eMMC can be also used as a regular SD card.
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