Re: [PATCH] fix save or snapshot at kernel loading time with HVM vm

[Keir Fraser <keir.fraser@eu.citrix.com>]

On 19/05/2010 07:44, "James (song wei)" <jsong@novell.com> wrote:

>>     Sorry for not descripting this issue clearly.  When I do save at the
>> beginning of HVM guest booting(first stage - loading kernel), I found
>> guest os destoryed after saving completely.

Well, that's expected isn't it? Normally, saving a guest should save its
state to a file and destroy the guest, so that the saved state can be safely
resumed later.

>> So I see the code and get this flow:
>> xc_save()( here, call this function, when loading the kernel at the time
>> of guest booting. Event channel haven't been initialized,so that go to
>> compat_suspend() path in suspend()(save.c) -->> then, notify  the thread
>> named saveInputHandler in xend with a string "suspend". so  that
>> dominfo.shutdown is invoked.

That's required. We need the guest to shutdown with state SHUTDOWN_suspend,
so that we can save a consistent snapshot of its state. If you skip the
shutdown then you break domain save in the absence of PV drivers. It will be
broken because the guest will continue to run while xc_save does its work --
hence it will not save a consistent snapshot of the guest state.

 -- Keir

>> So, VM shutdown after do saving operator.