[yocto] Yocto branches policy for concurrent SDK releases

[Zhenhua Luo]

Hi all,

Currently concurrent SDKs are on-going(e.g. SDK 1.5, T1040/T2080, LS1, etc), the same Yocto branch is used for multiple releases, there is conflict of Yocto recipes for different SDKs.

To resolve above issue, following branch mechanism will be used:

1. For those layers without conflict(poky, meta-oe, meta-virtualization and layers reused from community), same branch will be used and no extra branches need to be created, change for those layer should be upstreamed synchronously. 

2. For those layers with conflict, the branch specific to SDK are created, currently meta-fsl-ppc and meta-fsl-networking have conflict for different SDKs. Following branches will co-exist for such layers. 
   a. Yocto release branch: dylan, dora. the common changes for all SDKs should be submitted against this branch and cherry-picked to SDK specific branches. The changes should be upstreamed synchronously. 
   b. SDK specific branch: dylan-sdk1.5, dylan-t1_t2, etc. The SDK specific change should be submitted against SDK branch, when SDK is formally released, the changes will be upstreamed.  

Please let me know if any comment.  


Best Regards,

Zhenhua