RE: Transparent paravirtualization vs. xen paravirtualization (was:RE: [Xen-ia64-devel] IRQ management)

["Dong, Eddie" <eddie.dong@xxxxxxxxx>]

Tristan:
        Another thing like IOAPCI as Kevin pointed out is a must to be in HV as 
driver domain in future must have this feature. PMT is painful and urgent stuff 
too.
        See my comments embedded too.
Eddie

Tristan Gingold wrote:
> Le Mardi 25 Octobre 2005 07:49, Dong, Eddie a écrit :
>> Dan & all:
>>      This mail reminder me various stuff that XEN/IA64 needs to face
>> as the results of difference paravirtualization approach, it is time
>>      for us to have a revisit. 1: IPI and lSAPIC stuff.
>>              In deep virtualization solution (XEN/X86), xenlinux
>> never use direct IPI operation, instead it uses event channel. Same
>>              with APIC. XEN/IA64, using minimal paravirtualization (like
>> transparent virtualization), we have to implement IPI and APIC device
>> model in HV instead of changing xenlinux code. This becomes same with
>> VT-i implementation, so we and can reuse VT-i code, Tristan?.
> If everybody agree about this point, I will work on this (now).
Just make sure you are aware this one is dependent on virtual TLB stuff. I.e a 
vTLB for MMIO (PIB) can never go into VHPT. Same for other IOs like IOAPIC. 
> 
>>      2: VBD/VNIF
> [...]
>> 
>>      3: writable pagetable.
> [...]
> For these points, I don't know enough about Xen.  I may be able to
> comment later!
> 
>>      So, it looks like transparent paravirtualization can benfit in
>> reducing OSV's validation effort, but also introduces a lot of side
>> effort, especially with rapid development of Xen/X86 environment. Is
>> it time to think about more than transparent paravirtualization for
>> Xen/IA64? Or should we move to close more to Xen/X86?
> I agree with you.  I think we should stick to Xen/x86.
> 
> Tristan.


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