You can use AT!APPPARTCHG to configure or list the sizes of the partitions.
Total APP partition size:
261886 kB APPSBL,PAD,APPS,PAD,SYSTEM,PAD,USERDATA,PAD,USERAPP,PAD =
You can’t collapse them into the same space, but you can steal as much space as you want from the others. The partitions are used as follows:
APPSBL - the bootloader. Leave this one alone
APPS - kernel
SYSTEM - rootfs
USERDATA - We put the Legato framework here in some instances, but you don’t have to. You can reclaim all of this space if you like. As of 15.01 it is mounted as /mnt/legato.
USERAPP - The big writable area for your use (mounted as /mnt/flash)
If you run the command as a query you should see something like:
at!apppartchg? Total APP partition size: 261886 kB APPSBL,PAD,APPS,PAD,SYSTEM,PAD,USERDATA,PAD,USERAPP,PAD = 768,50,20000,384,50000,300,38000,2560,149440,384
That will list the sizes of the partitions. The one you care about for your rootfs is “SYSTEM”. Depending on how large it is you can steal some space from the subsequent partitions without too many consequences. e.g. increase size by 10MB …
Please refer to Flash partitions for more details.