RE: [Xen-devel] Re: APIC rework

["Zhang, Xiantao" <xiantao.zhang@xxxxxxxxx>]

Jeremy Fitzhardinge wrote:
> On 11/16/09 02:38, Zhang, Xiantao wrote:
>> Hi, Keir/Jeremy
>>    After you picking the two patches into upstream, we found it may
>> break old dom0 when assigned a level-triggered devices to a HVM
>> domain.  The casue is that, old dom0 can't provide trigger mode and
>> polarity when they do map_domain_pirq.  In attached patches, they
>> introduce a bit to indicate whether old dom0 or not.    
>> 
>> xen-introduce-a-bit-to-identify-dom0-type.patch:  for hypervisor.
>> 0001-x86-Introduce-a-bit-MAP_COMPAT-mode-for-MAP_PIRQ_TY.patch: for
>> pv ops dom0. 
>> 
> 
> Is there any way for the dom0 kernel to tell whether the hypervisor is
> implementing the new ABI, so it can choose how to set up interrupts.
> 
> MAP_COMPAT_BIT doesn't seem like a very good name, because it implies
> that setting it reverts to "compatible" behaviour.  I assume that
> leaving it clear enables the historical behaviour and setting it
> enables the new one (since old kernels won't be setting it).

Maybe better change to MAP_NEW_ABI_BIT ?  Since the hypervisor patch didn't 
change old code path after introducing this bit, so it is very easy and safe to 
backport to xen-3.4-testing tree, and make new dom0 be able to run top of it.  
:)
Xiantao
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