Re: newbus ioport usage

From: Nate Lawson (nate_at_root.org)
Date: 01/27/04

  • Next message: M. Warner Losh: "Re: newbus ioport usage" 
    Date: Tue, 27 Jan 2004 14:23:15 -0800 (PST)
To: "M. Warner Losh" <imp@bsdimp.com>

    On Tue, 27 Jan 2004, M. Warner Losh wrote:
    > In message: <20040127133251.W75080@root.org>
    > Nate Lawson <nate@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
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