Re: puc(4) man page update?

On Friday 04 July 2008 06:06:48 pm Marcel Moolenaar wrote:
> 
> On Jul 4, 2008, at 2:33 PM, John Baldwin wrote:
> 
> > On Friday 04 July 2008 03:31:41 pm Marcel Moolenaar wrote:
> >>
> >> On Jul 4, 2008, at 2:59 AM, Dmitry Morozovsky wrote:
> >>
> >>> doesn't splitting uart out of kernel broke serial console? Last time
> >>> I checked
> >>> it did.
> >>
> >> Yes, it does. The serial console is setup/initialized and
> >> used before pre-loaded modules are linked and/or usable.
> >> We don't have the support in place that allows you to boot
> >> without console until pre-loaded modules are initialized,
> >> at which time add a low-level console device is setup.
> >> It's not that hard to do, I think.
> >>
> >> So, currently low-level console drivers, such as dcons(4),
> >> sio(4) and uart(4) need to be compiled into the kernel.
> >> Consequently any devices/busses to which any of these can
> >> attach must be compiled into the kernel as well. Of these
> >> acpi(4) and puc(4) are good examples. acpi(4) is a good
> >> example because we use hints to work around the issue and
> >> have sio(4) attach to isa(4) instead...
> >
> > Actually, sio does attach to acpi0.  What happens for sio is that the
> > low-level console stuff is just doing bare-bones inb/outb anyway.   
> > sioX
> > devices do attach to acpi0 though just fine.
> 
> That's because sio(4) compiles-in the acpi bus attachment
> even if acpi is not compiled-in. That's cheating :-)

No, that's how new-bus works. :)  It's perfectly fine to do that.  The 
attachments get bound at runtime.  This is actually an important feature.  
It's part of why you can have multiple drivers with the same name (e.g. 
the "generic", "ACPI", and "OpenFirmware" PCI bus drivers).

-- 
John Baldwin