The default MMB Reference Image is design to use an A | B partition scheme, meaning there will always be a valid working copy on board to fail back to in case of failure. The Root File System ( including libraries, and language run times ) is on a separate partition from Customer Applications. Because of this, you can upgrade your application, the Root File System, or both. You can choose whether to use an MMB-provided Root File System with your Application or develop both pieces to meet your own requirements.
On request, this layout can be changed to support your needs. Alternatively, you can make this change on your own by editing the sources.
Partition Layout
| MTD: | UBI | Name: | Type: | Number of eraseblocks: | Character device major/minor: | Device is user writable: |
|---|---|---|---|---|---|---|
| 0 | N/A | UBoot | RAW | 16 (4194304 bytes, 4.0 MiB) | 90:0 | False |
| 1 | 0 | systemcfg | UBIFS | 40 (10321920 bytes, 9.84 MiB) | 250:1 | False |
| 1 | reserved | 40 (10321920 bytes, 9.84 MiB) | 250:2 | False | ||
2 | rootfs1 | 1118 LEBs (283918336 bytes, 270.8 MiB) | 250:3 | True | ||
3 | app1 | 610 LEBs (154910720 bytes, 147.7 MiB) | 250:4 | True | ||
4 | rootfs2 | 1118 LEBs (283918336 bytes, 270.8 MiB) | 250:5 | True | ||
| 5 | app2 | 610 LEBs (154910720 bytes, 147.7 MiB) | 250:6 | True | ||
6 | data | 464 LEBs (121634816 bytes, 116 MiB) | 250:7 | True | ||
| N/A | Reserve | RAW | 80 LEBs | N/A | ||
Descriptions
Root File System Partitions ( rootfs1 & rootfs2 )
Contains all libraries and run times needed. For instance, the Java JVM and full server class library are located here, so as to not impact available disk space for your applications. This partition is customizable to add or remove libraries according to your needs.
Application ( app1 & app2 )
Partition to contain all customer application code. This is currently mounted to /home/mmb/
Data ( data )
Gateway systems, and customers can use this region to store data that must persist after an upgrade of the Gateway Root File System, or Application partitions. Examples include: Wifi commissioning data, Cloud commissioning data, Error logs, Customer Databases
systemcfg ( systemcfg )
Used for storing unique Gateway data from the factory. In production is Read Only, but read/ writable on development units. Things like device serial number, mac address, manufacturing date code are all stored here.