Re: Xen 4.0.0-rc7 problem/hang with vt-d DMAR parsing

[Weidong Han <weidong.han@intel.com>]

Pasi Kärkkäinen wrote:
> On Tue, Mar 23, 2010 at 07:54:33PM +0000, Keir Fraser wrote:
>   
>> On 23/03/2010 19:37, "Pasi Kärkkäinen" <pasik@iki.fi> wrote:
>>
>>     
>>>> It's not impossible that the BIOS VT-d support is just broken (I assume
>>>> you've never tested VT-d on this particular type of system before).
>>>>         
>>> Yeah, I've never used VT-d on this system earlier, so it could just be broken
>>> BIOS.
>>> I guess Xen still shouldn't hang on it?
>>>       
>> We'd prefer to gracefully disable VT-d.
>>
>>     
>
> 4.0.0-rc7 (without any extra cmdline options) does disable vt-d and boot ok, 
> after 'hanging' for 30 seconds while parsing the DMAR tables.
>
> If I add "iommu=verbose" option for Xen, then it'll print huge amount of stuff 
> like I pasted earlier.. and it takes forever to print all that.
>   
The BIOS is likely broken. Could you dump the ACPI tables? Then we can 
confirm if it's BIOS issue. Maybe we can cook a patch to detect this 
issue (dmaru->address == 0), and handle it more gracefully. I will have 
a look at it.

Regards,
Weidong.
> Hmm.. wondering if the patch Jan just sent will help with that. 
> Sounds like it might help :)
>
> -- Pasi
>
>