Ingo Molnar wrote:
quoted text
> * Yinghai Lu <yinghai@kernel.org> wrote:
> 
>>> This feels like a hack that accidentally covers up the problem.  I 
>>> don't think we understand what's happening well enough.
>> yes, we need to figure out why when acpi=on, those BAR are cleared, 
>> before pci code try to scan and read BAR. (node early pic print out 
>> untouched, but after APCI subsystem is enabled, those BAR got 
>> clearred)
> 
> I'm wondering, how did it get cleared - some AML script told the kernel 
> to clear it?


[    0.012392] ACPI: Core revision 20090521
...
[    0.117217] ACPI FADT declares the system doesn't support PCIe ASPM, so disable it
[    0.117223] ACPI: bus type pci registered
[    0.117292] PCI: MCFG configuration 0: base e0000000 segment 0 buses 0 - 255
[    0.117297] PCI: Not using MMCONFIG.
[    0.117301] PCI: Using configuration type 1 for base access
[    0.118064] bio: create slab <bio-0> at 0
[    0.118995] ACPI: EC: Look up EC in DSDT
[    0.125066] ACPI: BIOS _OSI(Linux) query ignored
[    0.127077] ACPI: EC: non-query interrupt received, switching to interrupt mode
[    0.632002] ACPI: EC: missing confirmations, switch off interrupt mode.
[    0.793109] ACPI: Interpreter enabled
[    0.793114] ACPI: (supports S0 S3 S4 S5)
[    0.793139] ACPI: Using IOAPIC for interrupt routing
[    0.793193] PCI: MCFG configuration 0: base e0000000 segment 0 buses 0 - 255
[    0.795871] PCI: MCFG area at e0000000 reserved in ACPI motherboard resources
[    0.806419] PCI: Using MMCONFIG at e0000000 - efffffff
[    0.812767] ACPI: EC: GPE = 0x18, I/O: command/status = 0x66, data = 0x62
[    0.812772] ACPI: EC: driver started in poll mode
[    0.813206] ACPI: No dock devices found.
[    0.813879] ACPI: PCI Root Bridge [PCI0] (0000:00)

could be ACPI EC AML code related.

because with pci=nommconf, the BARs still get cleared.

need the reporter to boot with acpi.debug_layer=0x400000 acpi.debug_level=
to get more info

YH
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