Re: Regression introduced in v3.2.12 stable

[Joseph Salisbury <joseph.salisbury@canonical.com>]

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On 03/22/2012 05:26 PM, Greg KH wrote:
> On Thu, Mar 22, 2012 at 03:15:03PM -0400, Joseph Salisbury wrote:
>> I figured I'd send a heads up regarding a possible regression in v3.2.12
>> stable.  The issue prevents systems from booting.
>>
>> There have been a few bugs[0] reported against the Ubuntu kernel, which
>> was recently rebased to 3.2.12.  We're in the process of bisecting now
>> and will post an update..
> 
> What specifically happens here when the system does not boot?  Any error
> message?  Are you sure this isn't the known pci express issue showing up
> here?
> 
> Can you run 'git bisect' to trace it down to a specific patch please?
> 
> thanks,
> 
> greg k-h

Hi Greg,

Thanks for the response.

We did some bisecting/testing and identified the bad commit in 3.2.12 as
the following:

f043ddb60c84ea64a23b755004572afe922e653c PCI: ignore pre-1.1 ASPM
quirking when ASPM is disabled
diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
index 1cfbf22..24f049e 100644
- --- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -500,6 +500,9 @@ static int pcie_aspm_sanity_check(struct pci_dev *pdev)
        int pos;
        u32 reg32;

+       if (aspm_disabled)
+               return 0;
+
        /*
         * Some functions in a slot might not all be PCIe functions,
         * very strange. Disable ASPM for the whole slot


Building a test kernel with this commit reverted allows the machines to
boot.  I see there has already been some discussion on this commit[0]

Thanks,

Joe

[0] https://lkml.org/lkml/2012/3/19/408
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