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Date: Tue, 30 Apr 2002 20:51:31 -0700 (PDT)
From: Doug White <dwhite@resnet.uoregon.edu>
To: acpi-jp@jp.FreeBSD.org
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Subject: [acpi-jp 1606] HP OmniBook 6000 DSDT Loop
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Hello,

I posted some time ago about the broken DSDT on the HP OmniBook 6000
series laptops, with some dumps.

The other day I was discussing the problem again with Mike Smith and we
came to the conclusion that the problem was caused by an infinite loop
caused by the _REG function attempting to access PCI Config registers of a
child of itself, which causes the same _REG function to be called over and
over again.

However, I am at a loss as to how to fix this problem. The naieve way
would be to just allow the config register access so the initialization
can complete. However, this raises the question of whether such code is
correct and legal and if there are possible unintended consequences of
allowing such an access. I am curious if our top-down initialization sweep
is conformant with the specification and expected behavior for
ACPI-compliant operating systems.

The ACPI spec mentions that accesses to PCI Config space on a
specially-flagged bus must be allowed, but I'm not sure this is one of
those cases.

The ACPI dumps and some execution traces are at
http://www.freebsd.org/~dwhite/hp6000 for reference.

Thanks for any help!

Doug White                    |  FreeBSD: The Power to Serve
dwhite@resnet.uoregon.edu     |  www.FreeBSD.org

