Subject: Re: ISA direct config of ACPI devices
To: Jared D. McNeill <>
From: Matthias Drochner <>
List: tech-kern
Date: 11/22/2007 19:32:30 said:
> When it comes down to it, these ACPI / PNPBIOS enumerated devices are
> ISA  devices anyway.

No, they are made compatible of course, but the logical structures
within current chipsets are different. There is no address aliasing
anymore. And the devices don't go away if you disable the PCI-ISA
bridge. (Actually, the bridge's io/mem space enable bits are read only
on my box.) So having these devices attached to acpi (or whatever
virtual mainbus) reflects reality better than having them on isa.

> Like it or not, isa(4) is not going away any time soon on x86.

There are just some standard PC parts which depend on isa
(timer, intr controller etc) which could be as well hardwired
into common x86 code because they are part of what we know
as PC architecture. ISA also means indirect configuration, and
incomplete decoding, and that is dead code within most kernels
already now.

> structure to the device tree, required for 
> the power management branch.

As someone else already said, the assumption that logical
buses are equivalent to power domains does not always hold.

best regards

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