NEWBUS states

[Attilio Rao]

2009/9/5 M. Warner Losh <imp at bsdimp.com>:
> In message: <20090904.172310.-1939841993.imp at bsdimp.com>
>            "M. Warner Losh" <imp at bsdimp.com> writes:
> : OK.  Let me ponder based on that...  It might be better for this round
> : of changes to leverage off the device 'flags' field to indicate that
> : we're attaching/detaching.  This would not break the
> : device_is_attached() usage, and would solve the interlock problem
> : nicely.  While it isn't as aesthetically pleasing as the new states,
> : it would allow us to easily MFC it without API/ABI breakage.  This
> : field surely would be covered by the same set of locks as the state
> : field.
> :
> : I know that there's a good aesthetic argument to be made against this,
> : but on the other hand 'compatibility' hacks can violate one's
> : aesthetics.  We can migrate to a more pleasing state-based model in 9
> : and reduce the risk to other code from changing its semantics at this
> : late date.
>
> For a version of this hack, see
> http://people.freebsd.org/~imp/newbus-flags.diff

So you propose to offer the transition on the device flags instead
than the device states?
That is an interesting approach mostly because it won't require an ABI
breakage, but let me think about locking implications with it as I
want to review some code and came up with a patch/thoughts in some
hours.

Attilio


-- 
Peace can only be achieved by understanding - A. Einstein