When to burn those bridges

[John Baldwin]

On 10-Sep-2003 Doug Rabson wrote:
> On Wed, 2003-09-10 at 08:53, Eric Anholt wrote:
>> 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?
> 
> That is exactly what Keith did for the i830. I have his patches for it
> and I was supposed to review and commit them but they kind of got pushed
> to the bottom of the pile due to my recent house move. Would you like to
> do the honours? As far as I'm concerned, the patches are commit-ready
> apart from some minor violations of style(9) which I don't really care
> about but others might.

We still get texture corruption on the i830 that we are tracking down.
We also have several other problems with missed interrupts due to
lack of spl() usage in DRM.  I also have the patches and can try
to clean them up and commit them once Keith signs off on them.
Back to the hostb problem: notice that agp can't be kldloaded because
it can't attach to hostb because hostb is attached to it.  If agp
were a separate device instance from teh hostb device, then you could
kldload agp.

-- 

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