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

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

I didn't see segment fault, I saw some vcpu_translate faults, and it didn't 
impact the process of build. I'll look into this bug.

>-----Original Message-----
>From: Magenheimer, Dan (HP Labs Fort Collins) [mailto:dan.magenheimer@xxxxxx]
>Sent: 2005年10月14日 1:47
>To: Xu, Anthony
>Cc: xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
>Subject: RE: [Xen-ia64-devel] [PATCH] fixed some bugs to make xen0 more stable
>
>> > - 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).
>
>After further thought, I'm not going to argue this right now
>as it’s a very small fraction of context switch overhead.
>If it proves to be a problem, we can fix it back later.
>
>However, my testing is not going well so far.  I had just
>completed compiling Linux 15 times on tip (with Tristan's
>SMP patch) without any problems, but 2 of 5 runs so far with
>this new patch failed with segment faults.
>
>Any ideas of what might be causing this?  I can test with
>a subset of the patch...
>
>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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