https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=264414
Bug ID: 264414
Summary: ACPI resource allocation for buggy _CRS entries causes
"I/O range not supported" message
Product: Base System
Version: 13.1-STABLE
Hardware: Any
OS: Any
Status: New
Severity: Affects Some People
Priority: ---
Component: kern
Assignee: b...@freebsd.org
Reporter: crah...@gmail.com
There's detailed background information regarding this in bug #224096.
With the MacBook Pro in bug #224096, the range's maximum - minimum was equal to
the specified length.
But in the AMI 'Alaska' BIOS, the maximum is selected so that the length
includes both the top and bottom bytes, e.g. maximum - minimum + 1:
IO (Decode16,
0x0070, // Range Minimum
0x0077, // Range Maximum
0x01, // Alignment
0x08, // Length
)
And so, as a result, the "I/O range not supported" message is generated and no
resource is allocated.
This is in a ResourceTemplate for the _CRS for PCI0.
An sample ASL from the AMI 'Alaska' BIOS that illustrates the issue may be
found here:
https://github.com/linuxhw/ACPI/blob/master/Desktop/TONK/TN/TN1402/ABC6298CB633
I haven't noticed any malfunctions resulting from this other than the error
message, and correcting either the ASL or changing acpi_resource.c to set up
the resource anyway does not change this. I also don't know enough about how
the PCI controller uses this range to know if there should be a problem.
However, it appears that perhaps the correct solution to bug #224096 might be
not to check for both (high == (low + length)) and (high == (low + length -
1)), but rather to just set up the resource anyway, perhaps making note of the
compensation for the BIOS problem.
As this is hardly a new problem, and no one has reported any malfunctions
resulting from it, the issue is not so much this particular case but to provide
a reference for some future troubleshooter's search.
My incomplete understanding of the situation means I am only suggesting that
someone who knows more about this examine the issue.
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