[Qemu-devel] Save IDEState data to files when VM shutdown

[Huaicheng Li]

Hi all,

Please correct me if I’m wrong.

I made some changes to IDE emulation (add some extra structures to “struct 
IDEState") and want to save these info to files when VM shutdowns. So I can 
reload these info from files next time when VM starts.  According to my 
understanding, one IDEState structure is corresponding to one disk for VM and 
all available drives are probed/initialised by ide_init2() in hw/ide.c (I used 
qemu v0.11) during VM startup. It seemed that IDEState structure are saved to 
QEMUFile structure via pci_ide_save(), but I can only trace up to 
register_savevm(), where pci_ide_save() is registered as a callback. I can’t 
find where exactly this function starts execution or being called.  My 
questions are: 

(1). Does QEMUFile structure represent a running VM instance, through which I 
can access the IDE drive (struct IDEState) pointers ?

(2). When does qemu execute pci_ide_save()? 

(3). How does qemu handle VM shutdown? It seems ACPI event is sent to VM so 
guest OS will shutdown in the way like real OS running on real hardware. But 
how and where does qemu exactly handle this? I think I need to add my codes 
here. 

Any hints, suggestions would be appreciated. Thanks.

Huaicheng Li