Remove d_thread_t for 8.0

[M. Warner Losh]

In message: <200905201124.24747.jhb at freebsd.org>
            John Baldwin <jhb at freebsd.org> writes:
: On Wednesday 20 May 2009 10:59:24 am M. Warner Losh wrote:
: > In message: <200905121020.18497.jhb at freebsd.org>
: >             John Baldwin <jhb at freebsd.org> writes:
: > : In the same vein as purging BURN_BRIDGES stuff, is there any objection to 
: > : removing d_thread_t from 8.0?  It is intended as a compat shim to reduce 
: > : diffs with 4.x.  However, at this point drivers are not actively being 
: merged 
: > : back to 4.x, so I think it is no longer necessary.
: > 
: > It was also intended to allow easier sharing for folks that were using
: > FreeBSD 4.x, 5.x, etc.  I know that at least one user still has some
: > 4.x deployments, but I suspect that they are otherwise off 4.x so it
: > might not be a problem for them.  It would be yet another thing to
: > change when going from 7.x to 8.x for them...
: > 
: > We certainly should remove it from the drivers in the tree for 8.0.
: > Right now it is used in about a two dozen places.
: 
: Even in a shared driver I believe the function prototypes for devsw routines 
: would already have to be #ifdef'd due to the 'dev_t' -> 'struct cdev *' 
: change which does have a similar foo_t typedef to ease the transition.  Given 
: that, any code compiled for 7.0+ is already using a function prototype that 
: is not compatible with 4.x and there isn't a need for it to use d_thread_t.  
: They can just use 'struct thread *' always when using 'struct cdev *'.

Yes.  Let's eliminate it from the tree, and then talk about removing
it from conf.h :) There's other ways to paper over those issues, and I
know that they are relatively small in header files.  But those
headers are likely beyond the scope of what the project has to
support..

Warner