Sharing a shared state cache is possible; however, it needs to be approached with care. Not all changes are detected by the shared state cache implementation, and when this happens, some or all of the cache needs to be invalidated. This can cause problems when the state cache is being shared.

The recommendation in this case depends on the use case. Developers working on Yocto metadata should keep the shared state cache as default, separated per project.

However, validation and testing engineers, kernel and bootloader developers, and application developers would probably benefit from a well-maintained shared state cache.

To configure an NFS share drive to be shared among the development team to speed up the builds, you can add the following to your conf/local.conf configuration file:

SSTATE_MIRRORS ?= " 
     file://.* file:///nfs/local/mount/sstate/PATH"

To configure shared state cache sharing via HTTP, add the following to your conf/local.conf configuration file:

SSTATE_MIRRORS ?= "file://.* http://example.com/some_path/sstate-cache/PATH"

The expression PATH in these examples will get substituted by the build system with a directory named with the hash's first two characters.