Re: [Qemu-devel] [PATCH V15 4/5] i386: add a Virtual Machine Generation ID device

[Gal Hammer <ghammer@redhat.com>]

On 08/06/2015 16:55, Paolo Bonzini wrote:
>
>
> On 08/06/2015 15:52, Gal Hammer wrote:
>>>> 2. Is it possible to create a sysbus device using the "-device" command
>>>> line argument? I vaguely recall that it is not possible to do it and
>>>> that's the reason that I specifically add the device in the pc init.
>>>
>>> It's now possible, but it is somewhat complicated.  I think it's simpler
>>> to initialize this unconditionally and hide it (via ACPI _STA) if the
>>> vmgenid is all zeros.
>>
>> I didn't understand. I need the device to be a sysbus device so it won't
>> be found as an ISA or a PCI device by Windows. So I need to know what
>> ever or not it is possible to create a sysbus device using "-device". In
>> either way it won't be created if vmgenid is not given so no need to
>> hide it using _STA.
>
> Windows doesn't enumerate ISA devices when you create them with -device.
>   It just enumerates devices from the ACPI DSDT/SSDT.  So it's okay to
> make it an ISADevice, or to make it a part of another device (e.g. the
> ISA bridge or the power management device).  It's still ugly though.
>
> If you make it a sysbus device, you can just add it unconditionally, and
> define _STA so that Windows only sees it under the appropriate
> circumstances: for example, return 0 from _STA if the vmgenid (from the
> command line) is all zeroes.
>
> What is the command line option like?  Is it "-global vmgenid.uuid=foo"?

Yes. Right now it is a "-global" and I've been asked to change it to 
-"device", which I remember couldn't be done back then.

     Gal.

> Paolo
>