CHANGES file

[Mark Johnston]

On Fri, Mar 11, 2016 at 09:37:43AM -0800, Bryan Drewery wrote:
> In ports we have an UPDATING file that is targeted at users and a
> CHANGES file that is targeted at developers regarding API changes.
> 
> I would like to introduce a CHANGES file as it makes it simpler for
> developers to see what has changed without reading through all commit
> logs.  This is of great benefit for module writers and vendors who may
> even have customized some of the code in the tree.

+1

> 
> Some examples of recent changes that are otherwise undocumented:
> 
> 1. r295707 which introduced g_reset_bio() which *currently* is a wrapper
> around bzero, but may change.  At Isilon we had >1 lines of our own code
> affected by this change and I feel lucky I noticed it rather than
> leaving it to someone to discover years from now when it matters.
> 2. A lot of my recent share/mk changes may cause grief for vendors (but
> not likely out-of-tree builds).
> 3. callout_stop(9) return value.

Some other recent examples:

- DIOGDINFO removal
- a proc_set_cred() call is now needed to set the p_ucred field of a
  process
- callout_drain() return value
- with INVARIANTS, default use of the "trash" destructor in UMA zones