On Thu, Jun 24, 2021 at 6:09 PM Pintu Agarwal <pintu.ping@xxxxxxxxx> wrote: > I have one basic query related to UBIFS volumes on a system with NAND partition. There is no such thing as a UBIFS volume. Do you mean UBI volumes? > In short, how to detect a particular empty volume inside a system > partition while flashing the partition image? What do you mean by system partition? A MTD partition? > Suppose I have one big system partition that consists of 4-5 ubi > volumes inside it with varying sizes. > Lets say: > -- System Partition (ubi image) > - rootfs volume (ro, squashfs) > - data volume (rw, ubifs) > - firmware volume (ro, ubifs) > - some-other volume (ro, squashfs) So by system partition you mean the MTD partition that hosts UBI itself? > Consider that all these could be flashed together as part of > system.ubi image in a single shot from the bootloader. > Now, suppose, one of the volume image (say firmware) is missing or > remains empty (as you know we can have empty volumes). > > So, during system image flashing, we wanted to detect if one of the > volume (firmware) is empty. > Since this is an important volume, so we wanted to detect if this > volume is empty/missing we will abort flashing the system partition. > As there is no point in booting the system without this partition. > > So, I am exploring options, how can this be detected ? Read from the volume after flashing. If you get only 0xFF bytes it is empty. > I mean is there any kind of magic number or header information which > we can read to detect a particular empty volume ? > Can we get any information from just "system.ubi" image to indicate > about the volume information ? You'll need to perform a proper UBI scan on all blocks. If for the sad volume no LEBs have been found it is empty. > Also it could be possible that 2 or more volumes are empty, but we are > only concerned about one particular volume (firmware), so how to > detect particular volume ? I don't understand the use case. Is your image creation process so error prone that you can't be sure whether critical parts got included or not? -- Thanks, //richard
