[CentOS] Warning: Your BIOS is broken

[Robert Moskowitz]

On 02/22/2013 01:38 PM, John R Pierce wrote:
> On 2/21/2013 12:43 PM, Robert Moskowitz wrote:
>> :[Firmware Warn]: Your BIOS is broken; DMAR reported at address fed90000
>> returns all ones!
> I googled "Your BIOS is broken; DMAR reported at address fed90000
> returns all ones!" and got some related results.

My search fu was weak.  Very weak.

> this bug report (on FC12) says...  "yes, your bios is broken, but its
> not a bug, we worked around it"
> https://bugzilla.redhat.com/show_bug.cgi?id=896652

Well since Centos 6 is about equiv to F12, I guess I can 'live' with 
claim.  But then, how to stop the constant error reporting?

> on a similar/identical bug with Fedora FC17, someone suggested booting
> with iommu=off to work around this.

Where do I add this?

> on a similar debian bug report, it was stated that this error only
> happened when the BIOS setting for "VT-d" was enabled.    VT-d is only
> used to virtualized complete IO cards (like, dedicating a specified
> PCI-Express device to a given VM rather than handling it in the host and
> virtualizing the logical device).    If your BIOS has an option to turn
> VT-d off, you might try that.

I did a bit of googling to figure out where this might be in my bios and 
found:

http://jaredlxl.blogspot.com/2009/04/enable-amt-on-hp-dc7800-dc7900.html

Which took me to the right place in the bios and I see it already 
disabled.  So next is to try the iommu=off option.

Thanks for researching this for me.