PERFORCE change 94510 for review

[John Baldwin]

On Monday 03 April 2006 15:52, John-Mark Gurney wrote:
> John Baldwin wrote this message on Mon, Apr 03, 2006 at 15:03 -0400:
> > On Monday 03 April 2006 02:41, John-Mark Gurney wrote:
> > > http://perforce.freebsd.org/chv.cgi?CH=94510
> > > 
> > > Change 94510 by jmg at jmg_arlene on 2006/04/03 06:40:19
> > > 
> > > 	don't force the unit number to match the bus number, this breaks
> > > 	machines with multiple pci domains... how the alpha worked with
> > > 	this is beyond me (besides using custom pci bridge drivers?)
> > 
> > Alpha has issues with hoses.  That said, this might break some things. :(
> > If nothing else, it makes it nearly impossible now for people to get the
> > names of hints to override things like PCI routing via tunables correct.
> 
> just a bit less impossible than booting a multi domain box..
> 
> > I would prefer a structured solution that preserved the status quo on
> > machines w/o multiple domains.  Maybe have the unit number be something
> > like domain * X + bus number, where X is some arbitrary constant like
> > 100 or 1000 (those are better for human parsing).
> 
> Isn't this solved by something like wiring down unit numbers?  Where when
> you need to add a hint for interrupt routing you wire down the busses
> as necessasry?  Or maybe the fact that hints have to be wired, can't there
> be some more descriptive hint that is better than depending upon hard
> coded unit numbers?
> 
> As we've gotten away from static allocation for things like this, we
> now need to invent the next method for supporting hints in a dynamic
> environment..
> 
> Topic for the dev summit:  Static hints in a dynamic world?

Not hints in the classic sense.  But a tunable like this:

hw.pci0.4.INTA.irq=26

Right now the user can see what to use for 'pci0' right now
because it is the name of the pci device and it is deterministic
(it doesn't change across reboots for the most part, esp. if you
have systems with hot-plug pci that layout pci bus numbers
sparsely).

-- 
John Baldwin <jhb at FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve"  =  http://www.FreeBSD.org