Upcoming ABI Breakage in RELENG_7

[Max Laier]

On Wednesday 30 July 2008 11:47:34 David Southwell wrote:
> On Tuesday 29 July 2008 08:45:45 Ken Smith wrote:
...
> For those of us who are not as well informed and experienced  as others
> could someone please explain what is meant by an  ABI breakage, its
> implications and how to deal with them.

An Application Binary Interface (ABI) breakage means a change of a complex 
datatype, or a function prototype - in C usually the change of a struct in 
size or field sort order.  This change will effect all consumers of this 
Interface unless they are recompiled with the changed header files to also use 
the new interface.

The impact depends greatly on the interface that is being changed.  As Ken 
described in the initial mail this change is in the filesystem/vnode layer 
interface and thus will (only) concern consumers of that ABI.  The changed 
interface is also a kernel-only interface - that means that only 3rd party 
kernel modules will be affected.  I personally don't know of any 3rd party 
modules that muck about with filesystems (for which you can't get the source).  
That said, you might have to rebuild stuff like fuse after the breakage has 
happened.  I assume that port maintainers of affected (kernel module) ports 
will bump the port revision after the change to give you/portupgrade a hint.

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