RE: [Xen-ia64-devel] [PATCH] fixed some bugs to make xen0 more stable

["Xu, Anthony" <anthony.xu@xxxxxxxxx>]

Yes, I think we can use lazy PAL mapping, for meeting deadline, we didn't 
carefully consider this.

>-----Original Message-----
>From: Magenheimer, Dan (HP Labs Fort Collins) [mailto:dan.magenheimer@xxxxxx]
>Sent: 2005年10月13日 20:49
>To: Xu, Anthony
>Cc: xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
>Subject: RE: [Xen-ia64-devel] [PATCH] fixed some bugs to make xen0 more stable
>
>Thanks!  Looks like you found some very difficult bugs!
>
>> - Changing lazy PAL mapping switch to eager switch per domain
>> switch, since vti domain always depends on pal call.
>
>Can you explain this?  Aren't PAL calls always intercepted
>by Xen even with VTI?  It seems that the lazy PAL mapping
>approach should work for VTI also.  It's a shame to spend all
>those cycles on every context switch when PAL calls are so rare
>(after initial startup anyway).
>
>Thanks,
>Dan
>
>> -----Original Message-----
>> From: Xu, Anthony [mailto:anthony.xu@xxxxxxxxx]
>> Sent: Thursday, October 13, 2005 3:28 AM
>> To: Magenheimer, Dan (HP Labs Fort Collins)
>> Cc: xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
>> Subject: [Xen-ia64-devel] [PATCH] fixed some bugs to make
>> xen0 more stable
>>
>> Dan,
>>
>> When we debugged VTIdomainN, we found and fixed some bugs.
>> This patch is based on ver 7332
>>
>> - Consistence of region id mangling algrithm:
>>     - Metaphysical RID is not mangled, which may conflict
>> with other domain's virtual RID
>>     - Sometimes rr0 is mangled, but sometimes not
>>     - Sometimes only rid value is saved to
>> saved_rr0_metaphysical, but sometimes the whole value.
>>
>> - Nat bit consumption happens but handled as priv_emulate to
>> forward progress.But this is definitely wrong. We found
>> reason of nat consumption from fast_rfi,which doesn't save
>> unat again after spill guest states, and then use guest unat
>> to fill guest states when return.
>>
>> - In some corner case, timer interrupt handler won't update
>> itm and then return directly. When that happens, machine
>> timer interrupt disappears until guest timer interrupt sets
>> v_itm actively. But vti domain depends on ac_timer while the
>> latter will stop when above condition happens. Then if
>> current context is vti domain, context switch disappears and
>> machine halt.
>>
>> Also many compatibility issues to support non-vti and vti
>> domain are solved,eg:
>> - Changing lazy PAL mapping switch to eager switch per domain
>> switch, since vti domain always depends on pal call.
>> - evtchn_notify should also vcpu_wake target domain, since
>> vti domain may block for io emulation. Xenolinux is free of
>> this issue, since it's always runnable.
>>
>>
>> Signed-off-by Kevin Tian <kevin.tian@xxxxxxxxx>
>> Signed-off-by Anthony Xu <anthony.xu@xxxxxxxxx>
>>
>>
>> Thanks
>> Anthony
>>
>>

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