Re: [Qemu-devel] [PATCH 02/15] xen: Add xen_machine_fv

[Kevin Wolf <kwolf@redhat.com>]

Am 16.08.2010 16:04, schrieb Stefano Stabellini:
> On Mon, 16 Aug 2010, Kevin Wolf wrote:
>> Am 12.08.2010 16:09, schrieb stefano.stabellini@eu.citrix.com:
>>> From: Anthony PERARD <anthony.perard@citrix.com>
>>>
>>> Add the Xen FV (Fully Virtualized) machine to Qemu;
>>> this is groundwork to add Xen device model support in Qemu.
>>>
>>> Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
>>> Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
>>
>> Why does this need its own machine type? Shouldn't an HVM machine really
>> look like a PC? And indeed most of this code looks like a (slightly
>> outdated) copy of pc_piix.c with !pci_enabled code paths removed.
>  
> The main reason is that we need some xen specific initializations, as you can
> see from xen_init_fv.

Right, there are some more Xen specific things added later. However, the
main part of it is duplicated from pc_piix.c. I'm sure that with some
refactoring we could call these functions instead of copying and
modifying them. The problem with the latter is that they will inevitably
diverge even for changes that make sense for both.

I'm not even sure that the machine is the right place to do these Xen
specific initializations (expect for the Xen platform PCI device). As
far as I understand, the QEMUMachine is considered guest state whereas
most of these initializations concern host state.

> But considering that we have been asked to remove target-xen and that
> will cause a major refactoring of this series, xen_machine_fv could
> change significantly in the next iterations anyway...

Basically, the request to remove target-xen and my comment both aim in
the same direction, namely making Xen less special and integrate it
better in existing structures.

Kevin