What parts of UMA are part of the stable ABI?

John Baldwin jhb at freebsd.org
Wed Mar 18 15:59:58 UTC 2015

On Wednesday, March 18, 2015 11:19:21 AM Ryan Stone wrote:
> On Wed, Mar 18, 2015 at 10:24 AM, John Baldwin <jhb at freebsd.org> wrote:
> > I do think the normal zone callbacks passed to uma_zcreate() are too public
> > to change.  Or at least, you would need to do some crazy ABI shim where you
> > have a uma_zcreate_new() that you map to uma_zcreate() via a #define for
> > the API, but include a legacy uma_zcreate() symbol that older modules can
> > call (and then somehow tag the old function pointers via an internal flag
> > in the zone and patch UMA to cast to the old function signatures for zones
> > with that flag).
> >
> I really wasn't clear here.  I definitely don't think that changing the
> ctor, etc to accept a size_t is MFC'able, and I don't think that the
> problem (which is really only theoretical at this point) warrants an MFC to
> -stable.  I was talking about potentially doing it in a separate commit to
> head, but that does leave -stable and head with a different API.  This can
> be painful for downstream consumers to deal with, which is why I wanted
> comments.

I actually think the API change to fix the zone callbacks is fine to change
in HEAD.  I don't think that is too disruptive for folks who might be
sharing code across branches (they can use a local typedef to work around
it or some such).

John Baldwin

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