[yocto] Yocto Project feature/bug priority definition and related planning changes

[Liu, Song]

Hi All,

A while ago, we moved our features into the Bugzilla system and made managing bugs and features easier. But since then, we have been maintaining two sets of priority definitions for bugs and features. As we are using iterative process, we always learn, adjust and improve as we move forward. Now we are merging priority definitions for bugs and features. Thanks for the team's great contribution, now we have the new set of priority definitions below and I'll list related planning changes as well. All of these changes are also reflected on this wiki page: https://wiki.yoctoproject.org/wiki/Yocto_Project_Design_and_Development_Process 

Thank you all for your support. Please feel free to let me know if you have any questions or concerns.

Song


Definition of Priorities:
-------------------------

- High: crucial items
- Medium+: compared with medium ones, these are more important items that need more attention due to their bigger impact to system functions, build system, etc. 
- Medium: important items
- Low: nice to have items

How priorities are considered during planning:
---------------------------------------------

- Release planning: 
  - High: 
    * Required for the release and should have a specific milestone as the target milestone
    * Priority and schedule changes need CCB approval. 
  - Medium+: 
    * Required to have a release (major or point release) as the target milestone, but these items are not release blockers.
    * Encourage the team to schedule these items into milestones. But this is not required during release planning.
  - Medium: 
    * Required to have a release (major or point release) as the target milestone, but these items are not release blockers.
  - Low: No plan, leave to individuals
- Milestone planning:
  - Medium+/medium:  The team picks some of these items targeted for the release and schedule them to the current milestone. Medium+ items take higher priority. 
  - Low: no plan, leave to individuals

Impact to the Release criteria:
------------------------------

  - All high's for the target milestone must be completed for that milestone. Any priority or schedule changes for high's needs to go through CCB approval process. 
  - The majority of the medium+ items targeted for a release should be completed for the target release.


Existing Bugzilla item mapping:
-------------------------------

We will use the following as the guideline to assign existing features in Bugzilla to new priorities. At the same time, as the team looks through these items there may be some exceptions. We will try to complete this in the next week or so.

* Features: Severity = "Enhancement"
* Mapping:
  - "Old P4" = Target Milestone "Future", Priority "Low" 
  - "Old P3" = Priority "Low", Target Milestone can easily slip should roughly target a release though
  - "Old P2" = "Priority "Medium", should be more targeted milestone wise
  - "Old P1" = High + Priority Enhancements or bugs.
* Medium+
  - We may not assign any bugs to medium+ during this migration
  - We will mostly leave it to the team to decide which medium bugs need to be medium+ at this time