[Xen-devel] Pending Disk io requests during live migration

[Kaushik Bhandankar <kaushikb@xxxxxxxxxxxxx>]

Hello

I am trying to implement functionality in fully-virtualized xen wherein 
the responses to the pending disk I/O requests during live VM migration 
get trasnsferred to the new VMM form the old VMM. Specifically, I am 
looking at IDE disk (tools/ioemu/hw/ide.c)
Basically, ide.c:pci_ide_save() saves the state of the IDE disk in a 
QEMUFile and this file is sent over the network (can somebody point me 
to the code where this happens ??)) so that the new VMM (where the VM 
has migrated) invokes ide.c:pci_ide_load() to retrieve the IDE Disk 
contents form the file. As of now, the pending disk I/O requests do not 
get saved in this file so these pending disk I/O requests are not 
available when executing pci_ide_load().
I am still trying to figure out where the pending Disk I/O requests get 
stored in the VMM so that during live VM migration, these requests can 
be put in the QEMUFile (As mentioned above)
Also, looks like tools/ioemu/vl.c:register_savevm() seems to be invoking 
pci_ide_save()/pci_ide_load() methods but I am still looking for all 
possible scenarios in which pci_ide_save()/pci_ide_load() gets invoked.
Any help in locating the code would be greatly appreciated.

-Kaushik

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