Re: Commit dd6d87 breaks serial console

["Roger Pau Monné" <roger.pau@citrix.com>]

On 14/07/14 18:25, Andrew Cooper wrote:
> On 14/07/14 17:07, Roger Pau Monné wrote:
>> Hello,
>>
>> The following commit:
>>
>> commit dd6d87a4fcc8350c752e389abb3bcd8479c37555
>> Author: Jan Beulich <jbeulich@suse.com>
>> Date:   Fri Jun 20 10:26:37 2014 +0200
>>
>>     VT-d: drop redundant calls to invalidate_sync()
>>
>>     The call tree iommu_flush_iec_index() -> __iommu_flush_iec() already
>>     invokes invalidate_sync(). Removing the superfluous instances at once
>>     allows the function to become static.
>>
>>     Signed-off-by: Jan Beulich <jbeulich@suse.com>
>>     Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
>>     Acked-by: Yang Zhang <yang.z.zhang@intel.com>
>>
>> Breaks serial console on my box, this is all the output I get with this 
>> commit applied:
> 
> Are you sure you have bisected this correctly?
> 
> Unless there is some hardware side-effect of issuing two qinvalidate
> wait descriptors back-to-back, the change still looks to be good. 
> Alternately, are we missing a hardware erratum for your system?

Just for the record, setting iommu=no-intremap solves the problem, so
I'm quite sure I've bisected it right. This is on a Xeon W3550, I can
provide whatever other hardware information is needed.

Roger.