kern/41961: ISA devices should not attach to acpi0

[jmcneill%invisible.ca@localhost]

>Number:         41961
>Category:       kern
>Synopsis:       ISA devices should not attach to acpi0
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Aug 31 12:45:00 +0000 2009
>Originator:     Jared D. McNeill
>Release:        NetBSD 4.0_STABLE
>Organization:
        
>Environment:
        
        
System: NetBSD discovery.invisible.ca 4.0_STABLE NetBSD 4.0_STABLE (DISCOVERY) 
#2: Thu Apr 9 08:34:05 EDT 2009 
root%discovery.invisible.ca@localhost:/usr/src/sys/arch/i386/compile/DISCOVERY 
i386
Architecture: i386
Machine: i386
>Description:
        ACPI enumerates known devices on a system, but just because it can
        find ISA devices does not mean that driver instances should
        attach there. These devices are really children of isa (ISA bus),
        which is likely attached to a PCI-ISA bridge (pcib, ichlpcib, etc).
>How-To-Repeat:
        
>Fix:
        There are a few possible ways to resolve this, from best to worst:

        1. Attach the root PCI bus to acpi, and use the information in the
           ACPI decide tree to help enumerate devices on the system. This is
           the ideal approach, and will also require the most effort.
        2. Have ACPI enumerate all ISA devices and hand it off to MD code.
           MD code in turn uses isa_attach_hook to push in a list of known
           devices to isa, and drivers are adapted using ISA_DIRECT_CONFIG.
        3. Create a bus similar to isapnp but for ACPI devices.

        A proof of concept for option against -current can be found here:

        http://www.invisible.ca/~jmcneill/netbsd/isa-direct-config3.patch

>Unformatted: