[Xen-ia64-devel] First migration ! and RFCs...

[Tristan Gingold <Tristan.Gingold@xxxxxxxx>]

Hi,

I have just successfully migrated a domU from a tiger 4  (Montecito) to a 
tiger 2 (Madison).

This was of course a non-live migration.

I will start to work on live migration.

The live migration requires a bitmap of dirtied pages.  So the d bit (dirty 
bit) has to be virtualized.

I can see at least two issues now:

* When a dirty bit fault occurs Xen has to re-insert the pte.  This requires 
more information than available directly in the handler but these 
informations should be available in the VHPT.  However if the VHPT entry 
doesn't match, a page fault has to be injected which may be inefficient or 
prevent forward progress...

* Where is the bitmap ?  Within the data dirty fault, the virtual address is 
available but useless.  The physical address is available.  Because it is too 
sparse (like the memmap) the natural way is to put the bit within the memmap.
Or we can add a gpfn index within the VHPT and using a compact bitmap.

Thoughts ?

Tristan.

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