Hello!
Is it possible to store the environment inside a mtd partition when using a single qspi nand chip as storage? CONFIG_MTD_SPI_NAND=y
The idea is to separate the NAND into two system A/B.
1.Solution: mtdparts_nand0=2m(uboot),16m(system)
system will be an ubifs containing env+env_redundant + kernel_a+dtb_a+rootfs_a + kernel_b+dtb_b+rootfs_b. Uboot will read the env and load and start the selected a or b system.
With this solution ubifs will do all badblock handling. But system a and b are not really isolated. All will be lost if the one ubifs gets bad.
2.Solution: mtdparts_nand0=2m(uboot),512k(env),512k(env_redundant),8m(system_a),8m(system_b)
system_a/b will be ubifs containing kernel+dtb+rootfs. An environment outside the ubifs is needed to switch between system_a/b.
But I could not find a suitable option to store the environment outside the ubi mtd partitions when using MTD_SPI_NAND.
Here are my findings: CONFIG_ENV_IS_IN_NAND is used for the parallel NAND interface and wont work with MTD_SPI_NAND. CONFIG_ENV_IS_IN_SPI_FLASH is used for spi NOR flash and does not handle badblocks => also wont work. CONFIG_ENV_IS_IN_FLASH another flash subsystem??
Bad block handling seems to be only implemented for CONFIG_ENV_IS_IN_NAND using CONFIG_ENV_RANGE. Setting CONFIG_ENV_RANGE > CONFIG_ENV_SIZE will create tailing space for skipping bad blocks.
CONFIG_ENV_IS_IN_UBI will do badblock handling, but it would be a huge overhead to create an extra ubifs mtd partition only for the environment.
Has anyone already created the A/B system approach with the mtd spi nand interface and can give me some input? Am I missing something and there is a much simpler solution? Or would it be fine to use one big ubifs because ubi is reliable enough?