newbus ioport usage

[Nate Lawson]

On Tue, 27 Jan 2004, M. Warner Losh wrote:
> In message: <20040127133251.W75080 at root.org>
>             Nate Lawson <nate at root.org> writes:
> : > There's nothing magical about the acpi_sysresource device, and it can
> : > be relegated to the scrap-heap of history if needed.
> :
> : Well, the way we find out about the resources is through a pseudo-device
> : with a PNPID.  So it makes sense to use the normal device discovery method
> : to find these resources.  This leads me to do the allocation for the
> : parent by the acpi_sysresource0 attach method.
>
> This gets ugly.  The reason that I suggested not doing the discovery
> this way is because you want to allocate *ALL* resources up front
> before giving any to any children.  pci has issues with this right now
> that I'm working to fix.

I'm pretty sure there is no other way to know what resources acpi devices
will be using without evaluating the resource pseudo-device.  The other
way (which we currently do) is assume everything is available and let each
driver grab whatever is free and then attach the resource pseudo-device
last to claim all remaining acpi resources.  Unless you have a better
idea, the short-term approach will not change any of the above.  It will
just add the ability for acpi devices to later reclaim resources from
acpi0 (by having acpi_sysresource0 attach remaining resources to its
parent).

Allocating all resources up front would require multiple passes of the
namespace and I'm not ready to make that drastic of a change without some
more design work about how this fits in with the rest of FreeBSD (in
particular, PCI).

-Nate