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This page describe the partition layout of nand flash on radxa rock.

The partition is decided by the mtd parts in cmd line bootloader passed to the kernel, which is like this:

CMDLINE:console=ttyFIQ0 androidboot.console=ttyFIQ0 root=LABEL=linuxroot rw rootfstype=ext4 init=/sbin/init initrd=0x62000000,0x00800000 mtdparts=rk29xxnand:0x00002000@0x00002000(misc),0x00004000@0x00004000(kernel),0x00008000@0x00008000(boot),0x00010000@0x00010000(recovery),0x00020000@0x00020000(backup),0x00040000@0x00040000(cache),0x00200000@0x00080000(userdata),0x00002000@0x00280000(kpanic),0x00100000@0x00282000(system),0x00300000@0x00382000(linuxroot),-@0x00682000(user)

The partition must be 4M aligned due to the page size of rock/nand flash.

The layout of the dual boot image is as below:

Address Size Name Description
0x000000400000-0x000000800000 4M misc Android misc partition
0x000000800000-0x000001800000 16M kernel Obsolete Linux kernel partition, not used, keep it for compatibility*
0x000001000000-0x000002000000 16M boot Android boot.img(kernel+ramdisk)
0x000002000000-0x000004000000 32M recovery Android recovery/ Linux kernel + ramdisk
0x000004000000-0x000008000000 64M backup Backup partition, not used on radxa rock, keep it for compatibility
0x000008000000-0x000010000000 128M cache Android /cache partition
0x000010000000-0x000050000000 1024M userdata Android /data partition
0x000050000000-0x000050400000 4M kpanic For kernel panic dump
0x000050400000-0x000070400000 512M system Android /system partition
0x000070400000-0x0000d0400000 1536M linuxroot For the Linux rootfs
0x0000d0400000- - user Android internal flash as sdcard for storage
  • In previous android, the ramdisk(mounted as /) is in a separate partition, so we need two partitions, one for the kernel and the other for ramdisk, but the newer android pack together the kernel and the ramdisk into one single boot.img, so only one partition is needed