When to burn those bridges

Eric Anholt eta at lclark.edu
Wed Sep 10 00:53:46 PDT 2003

On Wed, 2003-09-10 at 00:15, John Baldwin wrote:
> On 09-Sep-2003 Doug Rabson wrote:
> > I haven't been paying much attention recently on release engineering
> > issues so probably I have missed something. When do people think is the
> > right time to branch off the 5.x line of development and set fire to the
> > bridges?
> Go ahead and kill the ISA compat drivers if you need to.  I do think
> that you can probably do this work in a p4 branch until it is ready
> and delay the killing of compat shims until then maybe.
> > This led me back to the idea of multiple inheritance in kobj/newbus.
> > Using multiple inheritance for the smbus re-work makes the chip drivers
> > much simpler since they don't have to explicitly list the 'parent'
> > methods in their method tables. The same thing goes for cardbus too. On
> > these lines, I went back and read through Justin's old inheritance
> > patches. These patches supported single inheritance for multiple
> > interfaces at the cost of changing the driver API considerably. I've
> > been tinkering with an alternative approach which supports multiple
> > inheritance at the class level, almost preserving the driver API while
> > changing the ABI slightly.
> Yes, please.  There is the same problem with agp(4) and the hostb(4)
> driver and agp(4) for Intel motherboards with onboard graphics and
> the drm(4) driver for the same graphics chip.

I thought we wanted agp(4) to replace hostb(4) when agp would attach. 
It's not the same problem for intel onboard graphics and the drm driver,
then, since we need both drivers for the DRM to work.  I think keithw
solved this by making the agp driver provide a "drmsub" child device
which the i8x0 DRM attaches to.  Would there be any problems with
putting that in CVS?

Eric Anholt                                eta at lclark.edu          
http://people.freebsd.org/~anholt/         anholt at FreeBSD.org

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