Re: [Qemu-devel] [Xen-devel] [PATCHv3] QEMU(upstream): Disable xen's use of O_DIRECT by default as it results in crashes.

[Paolo Bonzini]

Il 20/03/2013 11:37, George Dunlap ha scritto:
>> That is true. My guess is that nobody really migrates HVM guests without
>> PV drivers installed (it's not even possible on XenServer but xl let you
>> do that if you want to). When the PV drivers initialize at boot time,
>> the IDE disk is closed. Therefore we wouldn't have this problem.
>>
>> Maybe we should prevent HVM guest migration without PV drivers with xl
>> too. Ian, what do you think?
> 
> We should be able to make it safe if we just make sure that qemu does a
> metadata sync / FS sync when we ask qemu to write the save file.

To make it safe, just use cache=none.  There are downsides (for example
tmpfs does not support it), but perhaps you can use a global option or
environment variable to toggle the behavior.

Is xl still using the driver:subdriver:/path,readonly syntax?  That's
really inflexible compared to libvirt's XML...

Paolo