[CentOS] FYI - pci_mmcfg_init kernel error after upgrading to 5.6

Johnny Hughes johnny at centos.org
Mon Apr 25 21:15:57 UTC 2011


On 04/25/2011 10:19 AM, Ned Slider wrote:
> On 25/04/11 15:44, Windsor Dave L. (AdP/TEF7.1) wrote:
>> On 4/25/2011 10:26 AM, Johnny Hughes wrote:
>>> On 04/25/2011 08:58 AM, Windsor Dave L. (AdP/TEF7.1) wrote:
>>>> Just thought I'd pass along an error I received this weekend after
>>>> upgrading two servers to 5.6.  Both are HP Proliant DL380 servers
>>>> running 64-bit, but one is a G6 model and one is a G7.  After the
>>>> upgrade and the reboot to the 2.6.18-238.9.1.el5 kernel, both servers
>>>> displayed the following error at boot:
>>>>        "pci_mmcfg_init marking 256MB space uncacheable."
>>>>
>>>> Some Googling found me the following link:
>>>>        https://partner-bugzilla.redhat.com/show_bug.cgi?id=581933
>>>>
>>>> There are apparently performance implications due to this issue.
>>>> Fortunately, the solution is simple:  just boot with the kernel parameter
>>>>        acpi_mcfg_max_pci_bus_num=on
>>>>
>>>> If everyone is already familiar with this, please ignore. :-)
>>>>
>>>
>>> Supposedly this issue is fixed in the 5.6 kernel ... not introduced in it :D
>>>
>>> https://bugzilla.redhat.com/show_bug.cgi?id=581933
>>>
>>> However, the advise is good regardless of version of kernel.
>>>
>>
>>
>> Yes, I saw the reference to RHEL 5.5 in the bug description, but I never
>> saw the message before the upgrade to CentOS 5.6.  Hardware differences,
>> I guess.  The bug description mentions a Dell Precision.
>>
>> Best Regards,
>>
>> Dave Windsor
>>
> 
> I saw and reported the issue during QA for CentOS-5.6.
> 
> I think it's quite widespread, I saw it on generic Intel-based motherboards.
> 
> I've not had any issues applying the documented "fix" and have been 
> running that since January.

Well if this is wipe spread then we need to add this to the Release
Notes too ... I'll take care of that if it is not already there.

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